This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for...This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.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 paper is based on long term parameter measurements of the exhaust air heat pumps (EAHP) system in a new built apartment building. The building was equipped with an exhaust air ventilation system and exhaust air h...This paper is based on long term parameter measurements of the exhaust air heat pumps (EAHP) system in a new built apartment building. The building was equipped with an exhaust air ventilation system and exhaust air heat pump for ventilation heat recover. The results of the measurements show that the COP of the EAHP is mainly related to the temperature graph of the heating system and the supply temperature of domestic hot water (DWH). During the measurement period some other impact factors, such as the quality of maintenance, the nighttime temperature graph of the heating system, the reduction of the exhaust air flows in case of low temperatures, mistakes in designing and low building quality, have also played a role. An analysis of energy consumption shows that in winter conditions the COP is about 3.0 and in the transition period about 3.3. The energy recovery value of the EAHP is 0.5.展开更多
For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust...For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy storage.The proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and heat.With methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power generation.The thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2).Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is improved.Under the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 24.63%,respectively.The fuel saving rate(FSR)and the CO_(2) emission reduction(ER_(CO_(2)))achieve 32.97%and 25.33%,respectively.The research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.展开更多
The increase of insulation thickness(IT)results in the decrease of the heat demand and heat medium temperature.A mathematical model on the optimum environmental insulation thickness(OEIT)for minimizing the annual tota...The increase of insulation thickness(IT)results in the decrease of the heat demand and heat medium temperature.A mathematical model on the optimum environmental insulation thickness(OEIT)for minimizing the annual total environmental impact was established based on the amount of energy and energy grade reduction.Besides,a case study was conducted based on a residential community with a combined heat and power(CHP)-based district heating system(DHS)in Tianjin,China.Moreover,the effect of IT on heat demand,heat medium temperature,exhaust heat,extracted heat,coal consumption,carbon dioxide(CO_(2))emissions and sulfur dioxide(SO_(2))emissions as well as the effect of three types of insulation materials(i.e.,expanded polystyrene,rock wool and glass wool)on the OEIT and minimum annual total environmental impact were studied.The results reveal that the optimization model can be used to determine the OEIT.When the OEIT of expanded polystyrene,rock wool and glass wool is used,the annual total environmental impact can be reduced by 84.563%,83.211%,and 86.104%,respectively.It can be found that glass wool is more beneficial to the environment compared with expanded polystyrene and rock wool.展开更多
A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator, a condenser, an expansion valve, and a scroll e...A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is estab- lished, and experimental results show that the refrigerating capacity at the refrigerating temperature of-10℃ and the resorption time of 30 min is 1.95 kW, and the shaft power is 109.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.展开更多
基金supported by the National Key Research and Development Program of China[Grant No.2017YFE0116100]the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China[Grant No.KYCX20_2821].
文摘This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.
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 paper is based on long term parameter measurements of the exhaust air heat pumps (EAHP) system in a new built apartment building. The building was equipped with an exhaust air ventilation system and exhaust air heat pump for ventilation heat recover. The results of the measurements show that the COP of the EAHP is mainly related to the temperature graph of the heating system and the supply temperature of domestic hot water (DWH). During the measurement period some other impact factors, such as the quality of maintenance, the nighttime temperature graph of the heating system, the reduction of the exhaust air flows in case of low temperatures, mistakes in designing and low building quality, have also played a role. An analysis of energy consumption shows that in winter conditions the COP is about 3.0 and in the transition period about 3.3. The energy recovery value of the EAHP is 0.5.
基金financially supported by the Distinguish Young Scholars of the National Natural Science Foundation of China(No.52225601)the National Natural Science Foundation of China(Grant No.52006214)。
文摘For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy storage.The proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and heat.With methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power generation.The thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2).Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is improved.Under the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 24.63%,respectively.The fuel saving rate(FSR)and the CO_(2) emission reduction(ER_(CO_(2)))achieve 32.97%and 25.33%,respectively.The research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.
基金supported by the Scientific Research Project of Beijing Municipal Education Commission,China(KM201810017004)National Key R&D Program Project of China(No.2018YFC0704800)the“Engineering and Technology R&D Center of Clean Air Conditioning in Colleges of Shandong(Shandong Huayu University of Technology).”。
文摘The increase of insulation thickness(IT)results in the decrease of the heat demand and heat medium temperature.A mathematical model on the optimum environmental insulation thickness(OEIT)for minimizing the annual total environmental impact was established based on the amount of energy and energy grade reduction.Besides,a case study was conducted based on a residential community with a combined heat and power(CHP)-based district heating system(DHS)in Tianjin,China.Moreover,the effect of IT on heat demand,heat medium temperature,exhaust heat,extracted heat,coal consumption,carbon dioxide(CO_(2))emissions and sulfur dioxide(SO_(2))emissions as well as the effect of three types of insulation materials(i.e.,expanded polystyrene,rock wool and glass wool)on the OEIT and minimum annual total environmental impact were studied.The results reveal that the optimization model can be used to determine the OEIT.When the OEIT of expanded polystyrene,rock wool and glass wool is used,the annual total environmental impact can be reduced by 84.563%,83.211%,and 86.104%,respectively.It can be found that glass wool is more beneficial to the environment compared with expanded polystyrene and rock wool.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 51576120).
文摘A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is estab- lished, and experimental results show that the refrigerating capacity at the refrigerating temperature of-10℃ and the resorption time of 30 min is 1.95 kW, and the shaft power is 109.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.