The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for wa...The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for waste heat recovery.This review covers two aspects of high-efficiency TPV systems and industrial waste heat applications.At the system level,representative results of TPV complete the systems,while selective emitters and photovoltaic cells in the last decade are compiled.The key points of components to improve the energy conversion efficiency are further analyzed,and the related micro/nano-fabrication methods are introduced.At the application level,the feasibility of TPV applications in high-temperature industries is shown from the world waste heat utilization situation.The potential of TPV in waste heat recovery and carbon neutrality is illustrated with the steel industry as an example.展开更多
A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in s...A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in series for a centrifugal chiller in the paper. A finite-time thermodynamics method is used to set up the time series simulation model. As a result, an upper bound of recoverable condensation heat for the compound condensing process is obtained which is in good agreement with experimental result. And the result is valuable and useful to optimization design of condensing heat recovery.展开更多
Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer rec...Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver(FDR)of an air conditioning(A/C)system,which would otherwise go to waste.The study aims to build a set of thermoelectric generators(TEG)to collect the waste heat of the FDR and generate low-power electricity.A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging.The thermoelectric generator(TEGs)was installed on the FDR of the A/C unit.The test showed that climate conditions have a significant impact on the output power generated from the system.The results showed that the peak voltage recorded in the current study is 5.2 V per day(wet,cold,and wind weather)with an output power of 0.2 W.These values are acceptable for powering the load and charging a single battery with 3.5 V as the voltage increases battery 0.1 V/20 min charge.A case study of operating the emergency signs in a building was considered.The current heat recovery system is deemed to be easily installed and can be connected to a network of TEGs to produce more power.展开更多
Waste heat recovery from hot steel slag was determined in a granular bed through the combination of numerical simulation and an industrial test method.First,the effective thermal conductivity of the granular bed was c...Waste heat recovery from hot steel slag was determined in a granular bed through the combination of numerical simulation and an industrial test method.First,the effective thermal conductivity of the granular bed was calculated.Then,the unsteady-state model was used to simulate the heat recovery under three different flow fields(O-type,S-type,and nonshielding type(Nontype)).Second,the simulation results were validated by in-situ industrial experiments.The two methods confirmed that the heat recovery efficiencies of the flow fields from high to low followed the order of Nontype,S-type,and O-type.Finally,heat recovery was carried out under the Nontype flow field in an industrial test.The heat recovery efficiency increased from~76%and~78%to~81%when the steel slag thickness decreased from 400 and 300 to 200 mm,corresponding to reductions in the steel slag mass from 3.96 and 2.97 to 1.98 t with a blower air volume of 14687 m^(3)/h.Therefore,the research results showed that numerical simulation can not only guide experiments on waste heat recovery but also optimize the flow field.Most importantly,the method proposed in this paper has achieved higher waste heat recovery from hot steel slag in industrial scale.展开更多
Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high sola...Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high solar radiation areas.Furthermore,their dispatch capacities and yields can be affected by high electricity consumption,particularly at night.The present work aims to develop an off-design model that evaluates the hourly and annual performances of a parabolic trough power plant(PTPP)equipped with a waste heat recovery system.The study aims to compare the performances of this new layout with those of the conventional Andasol 1 plant,with the aim of assessing the improvements achieved in the new design.Based on the results,it can be concluded that the new layout has increased the annual generated power to almost 183 GWh(an increase of about 7.60% is achieved compared to the Andasol 1 layout that generates 169 GWh annually).Additionally,the proposed installation has achieved an efficiency of 20.55%,which represents a 7.87% increase compared to the previous design(19.05%).The Levelized Cost of Electricity(LCOE)of the new layout has been reduced by more than 5.8% compared to the Andasol 1 plant.Specifically,it has decreased from 13.11 to 12.35 c/kWh.This reduction in LCOE highlights the improved cost-effectiveness of the newlayout,making it amore economically viable option for generating electricity compared to the conventional Andasol 1 plant.展开更多
Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃...Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃.This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel,propane,natural gas,or heavy oil,leading to high energy costs and large carbon footprints.At the same time,the thermal energy content of a diesel generator sets(gen-sets)exhaust is known to be one-third of the total heating value of its combusted fuel.Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air.The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology,which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets)in an off-grid,cold,remote mine in Canada for heating of the mine intake air.Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates.After developing a thermodynamic model,the heat savings were calculated,and an economic feasibility evaluation was performed.The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75%of the heating demand for mine intake air,leading to a payback period of about eleven months or less for all scenarios.Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand,mainly in summertime,possibly allowing the system to eliminate fuel costs for intake air heating.展开更多
This study explores the potentials of employing an Organic Rankine Cycle (ORC) system with variable inlet guide vanes (VIV) turbine geometry designed on a GT-Suite platform for effective exhaust heat recovery (EHR) ap...This study explores the potentials of employing an Organic Rankine Cycle (ORC) system with variable inlet guide vanes (VIV) turbine geometry designed on a GT-Suite platform for effective exhaust heat recovery (EHR) application onboard passenger vehicles. The ORC model simulation was based on vehicle speed mode using R245fa as working fluid to assess the thermal performance of the ORC system when utilizing modified turbine geometry. Interestingly, the model achieved a very improved performance in contrast to the model without a modified turbine configuration. The results revealed the average 2.32 kW ORC net output, 4.93% thermal efficiency, 6.1% mechanical efficiency, and 5.0% improved brake specific fuel consumption (BSFC) for the developed model. As determined by the performance indicators, these promising results from the model study show the prospect of EHR technology application in the transportation sector for reduction in exhaust emissions and fuel savings.展开更多
In present,the wet-based pattern is mainly adopted to deal with the steel slag by steel plant at home and abroad,the wet-based technology has some defects;Wasting of water,pollution of the environment,and the slag has...In present,the wet-based pattern is mainly adopted to deal with the steel slag by steel plant at home and abroad,the wet-based technology has some defects;Wasting of water,pollution of the environment,and the slag has not been fully recycled.This paper presents a new method,which is aimed to realize dry granulation,waste heat recovery and comprehensive utilizing the steel slag.According to the ideas of wind quenching granulation,the heating slag from the converter furnace,was bring to the granulation heat exchange system,through the process of breaking in a container,the granulation heat exchange system has the functions of feeding continuously and heat exchange.The heat air,through the diversion tubes,could be recycled in removing the dust.The granulation slag could be bring to a confined roller,granulating and cooling secondarily.The roller export was connected to a magnetic separator.The separated iron could be recycled,and the remaining slag could also be reused as building materials,in process of stabilization and secondary magnetic separation.The heated air could be guided into the boiler to generate the steam,which can be used to generate electricity,or use as cleaned energy,realizing the target to recycle the waste heat in steel slag.The highlights of the new method are dry granulation and waste heat recovery.This paper states the process of heat exchange between the air and the steel slag in the system of granulation heat exchange in the new technical process.In theory,it has been proved reasonable with the the system of granulation heat exchange,and also the work conditions has been optimized.展开更多
The building energy consumption is an important part among the total society energy consumption,in which the energy consumption for air conditioning occupies almost 70%.The energy consumption of the air conditioning s...The building energy consumption is an important part among the total society energy consumption,in which the energy consumption for air conditioning occupies almost 70%.The energy consumption of the air conditioning system for fresh air handling can be saved effectively when the exhaust air energy could be recovered to preheat or precool the fresh air.Considering the install locations requirements on field,the pump-driven heat pipes(PHP)were developed as heat recovery ventilators(HRVs)and used in an existing experiment building in Beijing Urban.The thermal performance of the PHP HRVs was tested in real operation time periods under winter running mode.Both the power and heat consumption of the modular air handling units with and without HRVs were monitored and obtained,as well as the hourly power and heat consumption.The energy savings of HRVs were analyzed.The results indicate that the PHP HRVs can work steadily and meet the energy recovery need well.The temperature effectiveness of the HRVs can be kept from 60%to 70%.The test total energy saving rate was 24.48%,and the average hourly heat consumption reduced by 28.54%.The daily energy consumption can be saved by 118 kWh,and the energy savings can reach to 9440 kWh for a whole winter.展开更多
The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an ...The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an example, several waste heat recovery systems in the annealing furnaces are compared and their advantages and disadvantages are analyzed through different energy-saving technologies.展开更多
Syngas fuel generated by solar energy integrating with fuel cell technology is one of the promising methods for future green energy solutions to carbon neutrality.This paper designs a novel solar-driven solid oxide el...Syngas fuel generated by solar energy integrating with fuel cell technology is one of the promising methods for future green energy solutions to carbon neutrality.This paper designs a novel solar-driven solid oxide electrolyzer system integrated with waste heat for syngas production.Solar photovoltaic and parabolic trough collecter together drive the solid oxide electrolysis cell to improve system efficiency.The thermodynamic models of components are established,and the energy,exergy,and exergoeconomic analysis are conducted to evaluate the system’s performance.Under the design work conditions,the solar photovoltaic accounts for 88.46%of total exergy destruction caused by its less conversion efficiency.The exergoeconomic analysis indicates that the fuel cell component has a high exergoeconomic factor of 89.56%due to the large capital investment cost.The impacts of key parameters such as current density,operating temperature,pressure and mole fraction on system performances are discussed.The results demonstrate that the optimal energy and exergy efficiencies are achieved at 19.04%and 19.90%when the temperature,pressure,and molar fraction of H_(2)O are 1223.15 K,0.1 MPa,and 50%,respectively.展开更多
In order to improve the recovery and utilization rates of sinter waste heat effectively,the organic Rankine cycle(ORC)system with subcritical cycle was designed to recover the low-temperature sinter cooling flue gas w...In order to improve the recovery and utilization rates of sinter waste heat effectively,the organic Rankine cycle(ORC)system with subcritical cycle was designed to recover the low-temperature sinter cooling flue gas waste heat in an annular cooler for power generation.The thermodynamic,economic and multi-objective optimization models of ORC system were established,and R600a was selected as the ORC working medium.Subsequently,the variations in system thermodynamic performance and economic performance with the ORC thermal parameters were discussed in detail,and the optimal ORC thermal parameters were determined.The results show that the system net output power increases with increasing the evaporation temperature and decreasing the condensation temperature and increases first and then,decreases with the increase in superheat degree for a given flue gas outlet temperature in the evaporator,while the heat transfer area per unit net output power appears different variation trends in various ranges of flue gas outlet temperature.Taking the sinter cooling flue gas waste heat of 160℃as the ORC heat source,the optimal thermal parameters of ORC system were the flue gas outlet temperature of 90℃,the evaporation temperature of 95℃,the superheat degree of 10℃,and the condensation temperature of 28℃.展开更多
In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various appli...In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various applications, the wasted heat recovery concentrator PV/thermal(WHR CPVT) hybrid systems have been developed. They can provide both electricity and usable heat by combining thermal systems with concentrator PV(CPV) module, which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development of WHR CPVT systems. WHR CPVT systems with innovative design configurations, different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner. We aim to provide a global point of view on the research trends, market potential, technical obstacles, and the future work which is required in the development of WHR CPVT technology. Possibly, it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.展开更多
Hybrid electric vehicles(HEVs)are acknowledged to be an effective way to improve the efficiency of internal combustion engines(ICEs)and reduce fuel consumption.Although the ICE in an HEV can maintain high efficiency d...Hybrid electric vehicles(HEVs)are acknowledged to be an effective way to improve the efficiency of internal combustion engines(ICEs)and reduce fuel consumption.Although the ICE in an HEV can maintain high efficiency during driving,its thermal efficiency is approximately 40%,and the rest of the fuel energy is discharged through different kinds of waste heat.Therefore,it is important to recover the engine waste heat.Because of the great waste heat recovery performance of the organic Rankine cycle(ORC),an HEV integrated with an ORC(HEV-ORC)has been proposed.However,the addition of ORC creates a stiff and multi-energy problem,greatly increasing the complexity of the energy management system(EMS).Considering the great potential of deep reinforcement learning(DRL)for solving complex control problems,this work proposes a DRL-based EMS for an HEV-ORC.The simulation results demonstrate that the DRL-based EMS can save 2%more fuel energy than the rule-based EMS because the former provides higher average efficiencies for both engine and motor,as well as more stable ORC power and battery state.Furthermore,the battery always has sufficient capacity to store the ORC power.Consequently,DRL showed great potential for solving complex energy management problems.展开更多
An adsorption refrigeration system can be driven by low grade heat and uses natural refrigerant with the advantage of reducing the greenhouse gases emission.However,one of the weaknesses is its low efficiency and more...An adsorption refrigeration system can be driven by low grade heat and uses natural refrigerant with the advantage of reducing the greenhouse gases emission.However,one of the weaknesses is its low efficiency and more importantly its high cost.The recovery of internal waste heat becomes therefore very important in order to improve the coefficient of performance(COP).Analysis based on pinch technology can be helpful to optimal heat recovery operation.In this paper,temperature-heat diagrams and problem tables for adsorption refrigeration systems are proposed and analyzed using Pinch Technology.The results show that pinch point is located between beds and the main waste heat needs to be recovered between beds.Dynamic characteristic(time factor)of adsorption refrigeration system is the main resistance for heat recovery.The effect of pinch point temperature difference on the system COP is not distinct.Furthermore,when the driving temperature is 90°C,the COP of adsorption refrigeration via optimization of pinch analysis is 0.73 which is fairly comparable to Li Br-water absorption refrigeration system.Pinch Technology can be adopted in different types of adsorption refrigeration systems(two-bed,four-bed,mass recovery,et al.).展开更多
In this study,comprehensive evaluation of the technologies on waste heat recovery technologies for maritime applications has been carried out.We have focused our research on exhaust gas turbine system(EGT),thermodynam...In this study,comprehensive evaluation of the technologies on waste heat recovery technologies for maritime applications has been carried out.We have focused our research on exhaust gas turbine system(EGT),thermodynamic organic rankine cycle(RC),Kalina cycle(KC)and thermoelectric generators(TG),which are the most appropriate and most up-to-date techniques for recovering power from marine engines.Each technology has its own advantages and disadvantages,so the comprehensive evaluation of these technologies is essential to accurately determine which technology will be applied to which target.This belongs to the multi-criteria decision(MCDM)process.The combined assessment methodology,consisting of gray correlation and analysis hierarchy processes,has been applied to evaluate four waste heat recovery techniques in terms of technical,economic,social and environmental aspects.According to the comparison results,the exhaust gas turbine system has been evaluated as the most promising technology among the various WHR technologies that can be applied to marine engines.Sensitivity analysis suggests that if investment cost of TG falls to about the same level as the one of EGT,TG could be the best method among these technologies.Reduction of investment cost of TG technology could be realized by development of low cost thermoelectric material.We have analyzed the correlation between each cost through DOE analysis and investigate the effect of individual costs on the total cost.This work helps in identifying the most suitable heat recovery technologies for marine engine.展开更多
In the present study,the thermodynamic and economic performance of a combined thermodynamic cycle formed by an ORC and a Kalina cycle,which can simultaneously recover waste heat of exhaust gas and cooling water of mar...In the present study,the thermodynamic and economic performance of a combined thermodynamic cycle formed by an ORC and a Kalina cycle,which can simultaneously recover waste heat of exhaust gas and cooling water of marine engine,has been analyzed.Two typical marine engines are selected to be the waste heat source.Six economic indicators are used to analyze the economic performance of this combined thermodynamic cycle system with different marine engine load and under practical comprehensive operating condition of marine engine.The results of the present study show that the combined thermodynamic cycle system with R123 as organic working fluid has the best performance.The system with cis-butene has the worst economic performance.Under practical comprehensive operating conditions of ships,R123 has the shortest Payback Periods,which are 8.51 years and 8.14 years for 8 S70 ME-C10.5 engine and 5G95 ME-C10.5 engine,respectively.Correspondingly,payback Periods of Cyclopentane are 11.95 years and 11.90 years.The above values are much shorter than 25 years which are the lifetime of a marine ship.Under practical comprehensive operating conditions of ships,the combined cycle system can provide output power which is at least equivalent to 25%of engine power.Considering that R123 will be phased out in near future,cyclopentane may be its good successor.Cyclopentane can be used safely by correct handling and installing according to manufacturer's instructions.展开更多
At present,the dual-loop organic Rankine cycle(DORC)is regarded as an important solution to engine waste heat recovery(WHR).Compared with the conventional exergy analysis,the advanced exergy analysis can better descri...At present,the dual-loop organic Rankine cycle(DORC)is regarded as an important solution to engine waste heat recovery(WHR).Compared with the conventional exergy analysis,the advanced exergy analysis can better describe the interactions between system components and the irreversibility caused by economic or technical limitations.In order to systematically study the thermodynamic performance of DORC,the conventional and advanced exergy analyses are compared using an inline 6-cylinder 4-stroke turbocharged diesel engine.Meanwhile,the sensitivity analysis is implemented to further investigate the influence of operating parameters on avoidable-endogenous exergy destruction.The analysis result of conventional exergy analysis demonstrates that the priorities for the components that should be improved are in order of the high-temperature evaporator,the low-temperature turbine,the first low-temperature evaporator and the high-temperature condenser.The advanced exergy analysis result suggests that the avoidable exergy destruction values are the highest in the low-temperature turbine,the high-temperature evaporator and the high-temperature turbine because they have considerable endogenous-avoidable exergy destruction.The sensitivity analysis indicates that reducing the evaporation pinch point and raising the turbine efficiency can decrease the avoidable exergy destruction.展开更多
Oscillating heat pipes(OHP)which are constructed from a serpentine-arranged capillary tube possess a desirable aerodynamic form factor and provide for relatively high heat transfer rates via cyclic evaporation and con...Oscillating heat pipes(OHP)which are constructed from a serpentine-arranged capillary tube possess a desirable aerodynamic form factor and provide for relatively high heat transfer rates via cyclic evaporation and condensation of an encapsulated working fluid with no internal wicking structure required.In last two decades,OHP has been extensively investigated for its potential application in thermal management of various applications.This study presents an experimental investigation on the heat transfer performance of an atypically long finned OHP.The heat transfer performance of the proposed OHP was analyzed and compared with a bare tube OHP with similar overall dimensions.Results show that a unit row of finned OHP filled with n-pentane with fill ratio of 70%can recover up to(400±40)W of heat from a typical waste exhaust air stream.The additional pressure drop due to fins was estimated to be(6.8±2)Pa resulting in an increase of 1–2 W of fan power consumption.The average heat recovery rate via finned OHP was found to be almost 80%more than bare tube OHP filled with same working fluid with same fill ratio.展开更多
This paper introduces a kind of open cycle absorption heat wet flue gas heat recovery system,which use CaCl_(2) as the working medium.The system will use the wet heat recovery method and combined with an efficient hea...This paper introduces a kind of open cycle absorption heat wet flue gas heat recovery system,which use CaCl_(2) as the working medium.The system will use the wet heat recovery method and combined with an efficient heat pump system for flue gas as a heat source generator.Through direct contact with the solution in the absorber,the flue gas is going to carry out gas,liquid heat transfer between heat exchanger,realization of sensible heat and latent heat step by step.As the key part of the system,absorber is established by one-dimensional steady-state heat transfer and mass transfer model.This paper uses the finite difference method to model the discrete numerical methods,and an-alyzes the characteristics of heat and mass transfer in the absorber.We obtain the concentration curves of the three kinds of working medium’s temperature and flow along the height direction.We also analyze the influence of CaCl_(2) solution parameters changes on the absorption process,parsing the reason of the temperature change by analyzing the three working medium’s energy flow trend.We found that the temperature change of flue gas is non-monotonic,which decreases gradually in the range of absorption tower height 0-0.9 m,and then increases gradually.The reason for this change is that sensible heat exchange and latent heat exchange exist between flue gas and solution.Although such a change has an impact on the efficiency of the system,it prevents the"white smoke"from condensing in the air,which effectively protects the environment.Compared with conventional LiBr absorption heat pump,the system constructed in this paper has certain advantages in latent heat recovery,flue gas heat energy utilization,energy conservation and emission reduction and economy.展开更多
基金supported by the National Natural Science Foundation of China(No.52227813)China Postdoctoral Science Foundation(Nos.2023M740905,2023T160164)+3 种基金National Key ResearchDevelopment Program of China(No.2022YFE0210200)Natural Science Foundation of Heilongjiang Province(No.LH2023E043)the Fundamental Research Funds for the Central Universities(Nos.2022ZFJH04,HIT.OCEF.2021023)。
文摘The burning of fossil fuels in industry results in significant carbon emissions,and the heat generated is often not fully utilized.For high-temperature industries,thermophotovoltaics(TPVs)is an effective method for waste heat recovery.This review covers two aspects of high-efficiency TPV systems and industrial waste heat applications.At the system level,representative results of TPV complete the systems,while selective emitters and photovoltaic cells in the last decade are compiled.The key points of components to improve the energy conversion efficiency are further analyzed,and the related micro/nano-fabrication methods are introduced.At the application level,the feasibility of TPV applications in high-temperature industries is shown from the world waste heat utilization situation.The potential of TPV in waste heat recovery and carbon neutrality is illustrated with the steel industry as an example.
文摘A time series model is used in this paper to describe the progress of circulating direct condensation heat recovery of the compound condensing process (CCP) which is made of two water cooling condensing processes in series for a centrifugal chiller in the paper. A finite-time thermodynamics method is used to set up the time series simulation model. As a result, an upper bound of recoverable condensation heat for the compound condensing process is obtained which is in good agreement with experimental result. And the result is valuable and useful to optimization design of condensing heat recovery.
文摘Thermoelectric generators(TEGs)are considered promising devices for waste heat recovery from various systems.The Seebeck effect can be utilized to generate power using the residual heat emitted by the filter dryer receiver(FDR)of an air conditioning(A/C)system,which would otherwise go to waste.The study aims to build a set of thermoelectric generators(TEG)to collect the waste heat of the FDR and generate low-power electricity.A novel electrical circuit with two transformers is designed and fabricated to produce a more stable voltage for operation and charging.The thermoelectric generator(TEGs)was installed on the FDR of the A/C unit.The test showed that climate conditions have a significant impact on the output power generated from the system.The results showed that the peak voltage recorded in the current study is 5.2 V per day(wet,cold,and wind weather)with an output power of 0.2 W.These values are acceptable for powering the load and charging a single battery with 3.5 V as the voltage increases battery 0.1 V/20 min charge.A case study of operating the emergency signs in a building was considered.The current heat recovery system is deemed to be easily installed and can be connected to a network of TEGs to produce more power.
基金financially supported by the National Natural Science Foundation of China(No.51972019)the National Key Research and Development Program of China(No.2019YFC1905702)。
文摘Waste heat recovery from hot steel slag was determined in a granular bed through the combination of numerical simulation and an industrial test method.First,the effective thermal conductivity of the granular bed was calculated.Then,the unsteady-state model was used to simulate the heat recovery under three different flow fields(O-type,S-type,and nonshielding type(Nontype)).Second,the simulation results were validated by in-situ industrial experiments.The two methods confirmed that the heat recovery efficiencies of the flow fields from high to low followed the order of Nontype,S-type,and O-type.Finally,heat recovery was carried out under the Nontype flow field in an industrial test.The heat recovery efficiency increased from~76%and~78%to~81%when the steel slag thickness decreased from 400 and 300 to 200 mm,corresponding to reductions in the steel slag mass from 3.96 and 2.97 to 1.98 t with a blower air volume of 14687 m^(3)/h.Therefore,the research results showed that numerical simulation can not only guide experiments on waste heat recovery but also optimize the flow field.Most importantly,the method proposed in this paper has achieved higher waste heat recovery from hot steel slag in industrial scale.
文摘Concentrating Solar Power(CSP)plants offer a promising way to generate low-emission energy.However,these plants face challenges such as reduced sunlight during winter and cloudy days,despite being located in high solar radiation areas.Furthermore,their dispatch capacities and yields can be affected by high electricity consumption,particularly at night.The present work aims to develop an off-design model that evaluates the hourly and annual performances of a parabolic trough power plant(PTPP)equipped with a waste heat recovery system.The study aims to compare the performances of this new layout with those of the conventional Andasol 1 plant,with the aim of assessing the improvements achieved in the new design.Based on the results,it can be concluded that the new layout has increased the annual generated power to almost 183 GWh(an increase of about 7.60% is achieved compared to the Andasol 1 layout that generates 169 GWh annually).Additionally,the proposed installation has achieved an efficiency of 20.55%,which represents a 7.87% increase compared to the previous design(19.05%).The Levelized Cost of Electricity(LCOE)of the new layout has been reduced by more than 5.8% compared to the Andasol 1 plant.Specifically,it has decreased from 13.11 to 12.35 c/kWh.This reduction in LCOE highlights the improved cost-effectiveness of the newlayout,making it amore economically viable option for generating electricity compared to the conventional Andasol 1 plant.
文摘Underground mines in Arctic and Subarctic regions require the preheating of mine intake air during winter.The cold fresh air of those remote areas can be as severe as40℃ and commonly needs to be heated to around+3℃.This extensive amount of heating is usually provided by employing large-size air heaters,fueled by diesel,propane,natural gas,or heavy oil,leading to high energy costs and large carbon footprints.At the same time,the thermal energy content of a diesel generator sets(gen-sets)exhaust is known to be one-third of the total heating value of its combusted fuel.Exhaust heat recovery from diesel gen-sets is a growing technology that seeks to mitigate the energy costs by capturing and redirecting this commonly rejected exhaust heat to other applications such as space heating or pre-heating of the mine intake air.The present study investigated the possibility of employing a simple system based on off-theshelf heat exchanger technology,which can recover the waste heat from the exhaust of the power generation units(diesel gen-sets)in an off-grid,cold,remote mine in Canada for heating of the mine intake air.Data from a real mine was used for the analysis along with environmental data of three different location-scenarios with distinct climates.After developing a thermodynamic model,the heat savings were calculated,and an economic feasibility evaluation was performed.The proposed system was found highly viable with annual savings of up to C$6.7 million and capable enough to provide an average of around 75%of the heating demand for mine intake air,leading to a payback period of about eleven months or less for all scenarios.Deployment of seasonal thermal energy storage has also been recommended to mitigate the mismatch between supply and demand,mainly in summertime,possibly allowing the system to eliminate fuel costs for intake air heating.
文摘This study explores the potentials of employing an Organic Rankine Cycle (ORC) system with variable inlet guide vanes (VIV) turbine geometry designed on a GT-Suite platform for effective exhaust heat recovery (EHR) application onboard passenger vehicles. The ORC model simulation was based on vehicle speed mode using R245fa as working fluid to assess the thermal performance of the ORC system when utilizing modified turbine geometry. Interestingly, the model achieved a very improved performance in contrast to the model without a modified turbine configuration. The results revealed the average 2.32 kW ORC net output, 4.93% thermal efficiency, 6.1% mechanical efficiency, and 5.0% improved brake specific fuel consumption (BSFC) for the developed model. As determined by the performance indicators, these promising results from the model study show the prospect of EHR technology application in the transportation sector for reduction in exhaust emissions and fuel savings.
文摘In present,the wet-based pattern is mainly adopted to deal with the steel slag by steel plant at home and abroad,the wet-based technology has some defects;Wasting of water,pollution of the environment,and the slag has not been fully recycled.This paper presents a new method,which is aimed to realize dry granulation,waste heat recovery and comprehensive utilizing the steel slag.According to the ideas of wind quenching granulation,the heating slag from the converter furnace,was bring to the granulation heat exchange system,through the process of breaking in a container,the granulation heat exchange system has the functions of feeding continuously and heat exchange.The heat air,through the diversion tubes,could be recycled in removing the dust.The granulation slag could be bring to a confined roller,granulating and cooling secondarily.The roller export was connected to a magnetic separator.The separated iron could be recycled,and the remaining slag could also be reused as building materials,in process of stabilization and secondary magnetic separation.The heated air could be guided into the boiler to generate the steam,which can be used to generate electricity,or use as cleaned energy,realizing the target to recycle the waste heat in steel slag.The highlights of the new method are dry granulation and waste heat recovery.This paper states the process of heat exchange between the air and the steel slag in the system of granulation heat exchange in the new technical process.In theory,it has been proved reasonable with the the system of granulation heat exchange,and also the work conditions has been optimized.
基金supported by the Project of Science and Technology Program of Beijing Municipal Chao Yang District(CYSF2005,Zhun Li,http://www.bjchy.gov.cn/dynamic/notice/8a24fe83722fa7180172360a3f46044c.html).
文摘The building energy consumption is an important part among the total society energy consumption,in which the energy consumption for air conditioning occupies almost 70%.The energy consumption of the air conditioning system for fresh air handling can be saved effectively when the exhaust air energy could be recovered to preheat or precool the fresh air.Considering the install locations requirements on field,the pump-driven heat pipes(PHP)were developed as heat recovery ventilators(HRVs)and used in an existing experiment building in Beijing Urban.The thermal performance of the PHP HRVs was tested in real operation time periods under winter running mode.Both the power and heat consumption of the modular air handling units with and without HRVs were monitored and obtained,as well as the hourly power and heat consumption.The energy savings of HRVs were analyzed.The results indicate that the PHP HRVs can work steadily and meet the energy recovery need well.The temperature effectiveness of the HRVs can be kept from 60%to 70%.The test total energy saving rate was 24.48%,and the average hourly heat consumption reduced by 28.54%.The daily energy consumption can be saved by 118 kWh,and the energy savings can reach to 9440 kWh for a whole winter.
文摘The common problem of cold strip continuous annealing furnaces is high exhaust gas temperature and great energy consumption. Taking the cold-strip continuous annealing furnaces of Baosteel No. 4 cold mill plant as an example, several waste heat recovery systems in the annealing furnaces are compared and their advantages and disadvantages are analyzed through different energy-saving technologies.
基金supported by the National Natural Science Foundation of China(No.52276007)the Major Program of the National Natural Science Foundation of China(No.52090064)。
文摘Syngas fuel generated by solar energy integrating with fuel cell technology is one of the promising methods for future green energy solutions to carbon neutrality.This paper designs a novel solar-driven solid oxide electrolyzer system integrated with waste heat for syngas production.Solar photovoltaic and parabolic trough collecter together drive the solid oxide electrolysis cell to improve system efficiency.The thermodynamic models of components are established,and the energy,exergy,and exergoeconomic analysis are conducted to evaluate the system’s performance.Under the design work conditions,the solar photovoltaic accounts for 88.46%of total exergy destruction caused by its less conversion efficiency.The exergoeconomic analysis indicates that the fuel cell component has a high exergoeconomic factor of 89.56%due to the large capital investment cost.The impacts of key parameters such as current density,operating temperature,pressure and mole fraction on system performances are discussed.The results demonstrate that the optimal energy and exergy efficiencies are achieved at 19.04%and 19.90%when the temperature,pressure,and molar fraction of H_(2)O are 1223.15 K,0.1 MPa,and 50%,respectively.
基金support for this work provided by the National Natural Science Foundation of China(51974087 and 51904074)Anhui Provincial Natural Science Foundation(1908085QE203)+1 种基金Natural Science Research Foundation of Anhui Province University(2022AH050262)Science Research Foundation of Anhui Jianzhu University(2020QDZ02).
文摘In order to improve the recovery and utilization rates of sinter waste heat effectively,the organic Rankine cycle(ORC)system with subcritical cycle was designed to recover the low-temperature sinter cooling flue gas waste heat in an annular cooler for power generation.The thermodynamic,economic and multi-objective optimization models of ORC system were established,and R600a was selected as the ORC working medium.Subsequently,the variations in system thermodynamic performance and economic performance with the ORC thermal parameters were discussed in detail,and the optimal ORC thermal parameters were determined.The results show that the system net output power increases with increasing the evaporation temperature and decreasing the condensation temperature and increases first and then,decreases with the increase in superheat degree for a given flue gas outlet temperature in the evaporator,while the heat transfer area per unit net output power appears different variation trends in various ranges of flue gas outlet temperature.Taking the sinter cooling flue gas waste heat of 160℃as the ORC heat source,the optimal thermal parameters of ORC system were the flue gas outlet temperature of 90℃,the evaporation temperature of 95℃,the superheat degree of 10℃,and the condensation temperature of 28℃.
基金supported by the National Natural Science Foundation of China (51406051 and 51522602)the Beijing Municipal Science and Technology Project (Z161100002616039)the Fundamental Research Funds for the Central Universities (2016MS20)
文摘In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various applications, the wasted heat recovery concentrator PV/thermal(WHR CPVT) hybrid systems have been developed. They can provide both electricity and usable heat by combining thermal systems with concentrator PV(CPV) module, which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development of WHR CPVT systems. WHR CPVT systems with innovative design configurations, different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner. We aim to provide a global point of view on the research trends, market potential, technical obstacles, and the future work which is required in the development of WHR CPVT technology. Possibly, it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.
基金supported by the National Natural Science Foundation of China(Grant No.51906173)。
文摘Hybrid electric vehicles(HEVs)are acknowledged to be an effective way to improve the efficiency of internal combustion engines(ICEs)and reduce fuel consumption.Although the ICE in an HEV can maintain high efficiency during driving,its thermal efficiency is approximately 40%,and the rest of the fuel energy is discharged through different kinds of waste heat.Therefore,it is important to recover the engine waste heat.Because of the great waste heat recovery performance of the organic Rankine cycle(ORC),an HEV integrated with an ORC(HEV-ORC)has been proposed.However,the addition of ORC creates a stiff and multi-energy problem,greatly increasing the complexity of the energy management system(EMS).Considering the great potential of deep reinforcement learning(DRL)for solving complex control problems,this work proposes a DRL-based EMS for an HEV-ORC.The simulation results demonstrate that the DRL-based EMS can save 2%more fuel energy than the rule-based EMS because the former provides higher average efficiencies for both engine and motor,as well as more stable ORC power and battery state.Furthermore,the battery always has sufficient capacity to store the ORC power.Consequently,DRL showed great potential for solving complex energy management problems.
基金supported by the National Natural Science Foundation of China(Grant No.51906136)the Institute of Advanced Studies(IAS)of the University of Warwick in the UK(Grant No C5E3X56470T)Shanghai Sailing Program(Grant No.19YF1423100)。
文摘An adsorption refrigeration system can be driven by low grade heat and uses natural refrigerant with the advantage of reducing the greenhouse gases emission.However,one of the weaknesses is its low efficiency and more importantly its high cost.The recovery of internal waste heat becomes therefore very important in order to improve the coefficient of performance(COP).Analysis based on pinch technology can be helpful to optimal heat recovery operation.In this paper,temperature-heat diagrams and problem tables for adsorption refrigeration systems are proposed and analyzed using Pinch Technology.The results show that pinch point is located between beds and the main waste heat needs to be recovered between beds.Dynamic characteristic(time factor)of adsorption refrigeration system is the main resistance for heat recovery.The effect of pinch point temperature difference on the system COP is not distinct.Furthermore,when the driving temperature is 90°C,the COP of adsorption refrigeration via optimization of pinch analysis is 0.73 which is fairly comparable to Li Br-water absorption refrigeration system.Pinch Technology can be adopted in different types of adsorption refrigeration systems(two-bed,four-bed,mass recovery,et al.).
文摘In this study,comprehensive evaluation of the technologies on waste heat recovery technologies for maritime applications has been carried out.We have focused our research on exhaust gas turbine system(EGT),thermodynamic organic rankine cycle(RC),Kalina cycle(KC)and thermoelectric generators(TG),which are the most appropriate and most up-to-date techniques for recovering power from marine engines.Each technology has its own advantages and disadvantages,so the comprehensive evaluation of these technologies is essential to accurately determine which technology will be applied to which target.This belongs to the multi-criteria decision(MCDM)process.The combined assessment methodology,consisting of gray correlation and analysis hierarchy processes,has been applied to evaluate four waste heat recovery techniques in terms of technical,economic,social and environmental aspects.According to the comparison results,the exhaust gas turbine system has been evaluated as the most promising technology among the various WHR technologies that can be applied to marine engines.Sensitivity analysis suggests that if investment cost of TG falls to about the same level as the one of EGT,TG could be the best method among these technologies.Reduction of investment cost of TG technology could be realized by development of low cost thermoelectric material.We have analyzed the correlation between each cost through DOE analysis and investigate the effect of individual costs on the total cost.This work helps in identifying the most suitable heat recovery technologies for marine engine.
基金funded by the National Natural Science Foundation of China(Grant No.51506001)Beijing Municipal Education Commission(KM201710005029)。
文摘In the present study,the thermodynamic and economic performance of a combined thermodynamic cycle formed by an ORC and a Kalina cycle,which can simultaneously recover waste heat of exhaust gas and cooling water of marine engine,has been analyzed.Two typical marine engines are selected to be the waste heat source.Six economic indicators are used to analyze the economic performance of this combined thermodynamic cycle system with different marine engine load and under practical comprehensive operating condition of marine engine.The results of the present study show that the combined thermodynamic cycle system with R123 as organic working fluid has the best performance.The system with cis-butene has the worst economic performance.Under practical comprehensive operating conditions of ships,R123 has the shortest Payback Periods,which are 8.51 years and 8.14 years for 8 S70 ME-C10.5 engine and 5G95 ME-C10.5 engine,respectively.Correspondingly,payback Periods of Cyclopentane are 11.95 years and 11.90 years.The above values are much shorter than 25 years which are the lifetime of a marine ship.Under practical comprehensive operating conditions of ships,the combined cycle system can provide output power which is at least equivalent to 25%of engine power.Considering that R123 will be phased out in near future,cyclopentane may be its good successor.Cyclopentane can be used safely by correct handling and installing according to manufacturer's instructions.
基金supported by the Science and Technology Major Project of Tibet of China(Grant No.XZ201801-GA-03)the Natural Science Foundation of Hunan Province,China(Grant No.2018JJ2399)。
文摘At present,the dual-loop organic Rankine cycle(DORC)is regarded as an important solution to engine waste heat recovery(WHR).Compared with the conventional exergy analysis,the advanced exergy analysis can better describe the interactions between system components and the irreversibility caused by economic or technical limitations.In order to systematically study the thermodynamic performance of DORC,the conventional and advanced exergy analyses are compared using an inline 6-cylinder 4-stroke turbocharged diesel engine.Meanwhile,the sensitivity analysis is implemented to further investigate the influence of operating parameters on avoidable-endogenous exergy destruction.The analysis result of conventional exergy analysis demonstrates that the priorities for the components that should be improved are in order of the high-temperature evaporator,the low-temperature turbine,the first low-temperature evaporator and the high-temperature condenser.The advanced exergy analysis result suggests that the avoidable exergy destruction values are the highest in the low-temperature turbine,the high-temperature evaporator and the high-temperature turbine because they have considerable endogenous-avoidable exergy destruction.The sensitivity analysis indicates that reducing the evaporation pinch point and raising the turbine efficiency can decrease the avoidable exergy destruction.
文摘Oscillating heat pipes(OHP)which are constructed from a serpentine-arranged capillary tube possess a desirable aerodynamic form factor and provide for relatively high heat transfer rates via cyclic evaporation and condensation of an encapsulated working fluid with no internal wicking structure required.In last two decades,OHP has been extensively investigated for its potential application in thermal management of various applications.This study presents an experimental investigation on the heat transfer performance of an atypically long finned OHP.The heat transfer performance of the proposed OHP was analyzed and compared with a bare tube OHP with similar overall dimensions.Results show that a unit row of finned OHP filled with n-pentane with fill ratio of 70%can recover up to(400±40)W of heat from a typical waste exhaust air stream.The additional pressure drop due to fins was estimated to be(6.8±2)Pa resulting in an increase of 1–2 W of fan power consumption.The average heat recovery rate via finned OHP was found to be almost 80%more than bare tube OHP filled with same working fluid with same fill ratio.
基金This paper is supported by The National Natural Science Foundation of China.The project approval number is 52076050.In addition,we would like to thank Jiyou Lin and Jianfeng Wu for their support to this paper.
文摘This paper introduces a kind of open cycle absorption heat wet flue gas heat recovery system,which use CaCl_(2) as the working medium.The system will use the wet heat recovery method and combined with an efficient heat pump system for flue gas as a heat source generator.Through direct contact with the solution in the absorber,the flue gas is going to carry out gas,liquid heat transfer between heat exchanger,realization of sensible heat and latent heat step by step.As the key part of the system,absorber is established by one-dimensional steady-state heat transfer and mass transfer model.This paper uses the finite difference method to model the discrete numerical methods,and an-alyzes the characteristics of heat and mass transfer in the absorber.We obtain the concentration curves of the three kinds of working medium’s temperature and flow along the height direction.We also analyze the influence of CaCl_(2) solution parameters changes on the absorption process,parsing the reason of the temperature change by analyzing the three working medium’s energy flow trend.We found that the temperature change of flue gas is non-monotonic,which decreases gradually in the range of absorption tower height 0-0.9 m,and then increases gradually.The reason for this change is that sensible heat exchange and latent heat exchange exist between flue gas and solution.Although such a change has an impact on the efficiency of the system,it prevents the"white smoke"from condensing in the air,which effectively protects the environment.Compared with conventional LiBr absorption heat pump,the system constructed in this paper has certain advantages in latent heat recovery,flue gas heat energy utilization,energy conservation and emission reduction and economy.