Research on Operation Optimization of Heating System Based on Electric Storage Coupled Solar Energy and Air Source Heat Pump

For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.

Modeling and Optimization of Solar Collector Design for the Improvement of Solar-Air Source Heat Pump Building Heating System

To enhance system stability,solar collectors have been integrated with air-source heat pumps.This integration facilitates the concurrent utilization of solar and air as energy sources for the system,leading to an improvement in the system’s heat generation coefficient,overall efficiency,and stability.In this study,we focus on a residential building located in Lhasa as the target for heating purposes.Initially,we simulate and analyze a solar-air source heat pump combined heating system.Subsequently,while ensuring the system meets user requirements,we examine the influence of solar collector installation angles and collector area on the performance of the solar-air source heat pump dual heating system.Through this analysis,we determine the optimal installation angle and collector area to optimize system performance.

Design and Analysis of a Small Sewage Source Heat Pump Triple Supply System

Based on the characteristics of sewage from beauty salons,a simulation model of a small sewage source heat pump triple supply system that can be applied to such places is established to optimize the operating conditions of the system.The results show that with the increase of sewage temperature and flow,the performance of the system also increases.In summer conditions,the system provides cooling,recovers waste heat and condensed heat from sewage,with a COP value of 8.97;in winter conditions,the system heats and produces hot water,with a COP value of 2.44;in transitional seasons,only hot water is produced.The COP value is 2.75.Compared with the traditional systems which refers to the air source heat pump and hot water boiler system currently used in beauty salons,this system can save energy by 50.9%.

Possibilities of Reducing Energy Consumption by Optimization of Ground Source Heat Pump Systems in Babylon, Iraq

Iraq is located in the Middle East with an area that reaches 437,072 km2 and a population of about 36 million. This country is suffering from severe electricity shortage problems which are expected to increase with time. In this research, an attempt is made to minimize this problem by combining the borehole thermal energy storage (BTES) with a heat pump, the indoor temperature of a residential building or other facility may be increased or reduced beyond the temperature interval of the heat carrier fluid. Due to the relatively high ground temperature in Middle Eastern countries, the seasonal thermal energy storages (STES) and ground source heat pump (GSHP) systems have a remarkable potential, partly because the reduced thermal losses from the underground storage and the expected high COP (ratio of thermal energy gain to required driving energy (electricity)) of a heat pump, partly because of the potential for using STES directly for heating and cooling. In this research, groundwater conditions of Babylon city in Iraq were investigated to evaluate the possibility of using GSHP to reduce energy consumption. It is believed that such system will reduce consumed energy by about 60%.

The Application of the Ground Source and Air-to-Water Heat Pumps in Cold Climate Areas

This article gives an overview of using the ground source heat pump (GSHP) and air-to-water heat pump (A&WHP) in cold climate areas for heating and for domestic hot water production of buildings. Computer simulation and analysis were carried out for a typical detached house, with 200 m2 of living area, the heat demand of 9 kW and the average heat demand for DHW production of 1 kW. In heating period the average Coefficient of Performance (COP) of the A&WHP is considerably lower than COP of the GSHP.

Performance and Optimization of Air Source Heat Pump Water Heater with Cyclic Heating

A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.

Zoning operation of energy piles to alleviate the soil thermal imbalance of ground source heat pump systems

Energy piles have attracted increasing interest for application in ground source heat pumps,because it is environment-friendly,energy-efficient,and without additional drilling cost.However,when there is a large dif-ference between the heating and cooling loads,the system will suffer from a soil thermal imbalance which may further decline the system performance and even cause a system failure.A hybrid ground source heat pump sys-tem that integrates auxiliary equipment can solve the problem,however,it needs additional investment and a complicated control strategy.In this paper,the zoning operation of energy piles can effectively improve the tem-perature recovery ability of soil in the energy pile group and thus alleviate the soil thermal imbalance.Specifically,a heating-dominated residential building in Beijing is selected for a case study,with 144 energy piles arranged in a 12×12 layout.An analytical model of the spiral-coil energy pile group with seepage will be adopted,which can consider the groundwater flow,the geometry of spiral coils,and the thermal interaction among different energy piles,achieving high calculation accuracy and fast calculation speed.Based on this analytical energy pile model,a system model will be built to investigate the system performance influenced by different zoning operation strategies.Results show that intensive heat injection into the center of the pile group(Strategy 2 and Strategy 3)or heat extraction from the outer layer of the pile group(Strategy 4)can relieve the cold accumulation.Strategy 2 can relieve the outlet temperature decline from 5.54℃ to 4.46℃ and improve the heating COP from 3.297 to 3.423 compared to the conventional full operation strategy.Although the annual heat pump COP of Strategy 2 is a little lower than that of conventional full operation strategy,Strategy 2 has the shortest unmet heating or cooling time.Therefore,the proposed zoning operation strategy can achieve good system efficiency and excellent system reliability compared to the conventional strategy.

Dynamic Simulation and Performance Analysis on Multi-Energy Coupled CCHP System

Although the Combined Cooing,Heating and Power System(hereinafter referred to as“CCHP”)improves the capacity utilization rate and energy utilization efficiency,single use of CCHP system cannot realize dynamic matching between supply and demand loads due to the unbalance features of the user’s cooling and heating loads.On the basis of user convenience and wide applicability of clean air energy,this paper tries to put forward a coupled CCHP system with combustion gas turbine and ASHP ordered power by heat,analyze trends of such parameters as gas consumption and power consumption of heat pump in line with adjustment of heating load proportion of combustion gas turbine,and optimize the system ratio in the method of annual costs and energy environmental benefit assessment.Based on the analysis of the hourly simulation and matching characteristics of the cold and hot load of the 100 thousand square meter building,it is found that the annual cost of the air source heat pump is low,but the energy and environmental benefits are poor.It will lead to 6.35%shortage of cooling load in summer.Combined with the evaluation method of primary energy consumption and zero carbon dioxide emission,the coupling system of CHHP and air source heat pump with 41%gas turbine load ratio is the best configuration.This system structure and optimization method can provide some reference for the development of CCHP coupling system.

Data-driven sensitivity analysis and electricity consumption prediction for water source heat pump system using limited information

The studies on predicting the energy consumption of air conditioning systems are meaningful to building energy conservation and management. Generally, the more comprehensive the building information is, the easier the prediction model can be developed. However, it is very difficult to get detailed information about existing/old buildings (information-poor buildings), it is a big challenge to predict the energy consumption accurately by limited information. This study aims to predict the electricity consumption of the water source heat pump system of an office building based on meteorological data. The key variables are selected by error analysis and sensitivity analysis, and the effects of each variable on the models’ prediction performance can be obtained. Besides, the prediction models are established by support vector regression algorithm and trained by the local meteorological data. The results show that the positive and negative variables can be identified, and these positive variables are responsible for more than 70% of the total importance. Moreover, the root mean square error falls to 4.6044 from 7.8227 and the relative square error falls to 0.1494 from 0.4313 when the negative inputs are removed. And the errors reduce further to 4.1160 and 0.1194 by parameter optimization.

Prediction and parametric analysis of 3D borehole and total internal thermal resistance of single U-tube borehole heat exchanger for ground source heat pumps

The borehole and total internal thermal resistance are both significant parameters in evaluating the thermal performance of the ground source heat pump.This study aimed to obtain the accurate correlation of the 3D borehole and total internal thermal resistance(R_(b,3D)and R_(a,3D))and analyze the impacts of parameters on the R_(b,3D)and R_(a,3D).Firstly,eight parameters affecting the R_(b,3D)and R_(a,3D),including the borehole diameter,pipe diameter,pipe-pipe distance,borehole depth,soil thermal conductivity,grout thermal conductivity,pipe thermal conductivity,and fluid velocity inside the pipe,were considered and an L-54 design matrix was generated.Then,the 3D numerical model,coupling with the four-resistance model,was proposed to calculate R_(b,3D)and R_(a,3D)for each case.After that,the response surface methodology was employed to obtain and verify the correlation of R_(b,3D)and R_(a,3D),which were compared with the existing resistance calculation methods.Lastly,analysis of variance was carried out to reveal parameters that have statistically significant impacts on the R_(b,3D)and R_(a,3D).Results show that the rationality and accuracy of the correlation of R_(b,3D)and R_(a,3D)can be verified by the determination coefficient and P value of regression model,as well as the P value of lack-of-fit.The existing resistance calculation methods are more or less inaccurate and the discrepancies in some cases can be up to 86.74%and 111.35%for the borehole and total internal thermal resistance.The pipe and grout thermal conductivity,pipe and borehole diameter,and the pipe-pipe distance can be seen as the significant contributory factors to the variation of R_(b,3D)and R_(a,3D).

Water pumping analysis and experimental validation of beach well infiltration intake system in a seawater source heat pump system

Based on energy conservation equation and Darcy＇s law, a model of beach well infiltration intake system applied in a seawater source heat pump system was established. The model consists of the seawater seepage and the heat transfer process. A porous medium model in a software named FLUENT was applied to simulate the seepage and the heat transfer process. This model was also validated by field experiment conducted on the seashore in Tianjin, China. The maximum relative error between simulation results and experimental results was 2.1% （less than 5%）, which was acceptable in engineering applica- tion. The porosity and coefficient of thermal conductivity of the aquifer soil were determined to be 0.49 W/（m. K） and 1.46W/（m.K）, respectively in the simulation. In addition, the influencing factors of pumping water of beach well were also analyzed. The pumping water was found to increase when the distance between the beach well and the impervious boundary becomes longer, when the distance between the beach well and the supplying water source shortens, when the diameter of the beach well enlarges, and the drawdown enlarges.

Thermal Efficiency Optimization of a Ground Source Heat Pump System by Assistant Preheating/Precooling: A Case Study on a Heating-Load Dominated Building

Operation strategies of Ground Source Heat Pump System(GSHPS) such as continuous or intermittent approaches have been extensively studied. In this work, a novel strategy was proposed to maximize the energy efficiency of GSHPS. In this approach, the buildings was first air-conditioned by the preheating/precooling mode and the rest thermal load was covered by the heat pump(HP) mode. The system performance can then be optimized by considering the combination of these two operating modes. A case study was made to examine the thermal performance of a GSHPS installed in Nuremberg, Germany. Thermal performance of the HP and the preheating/precooling operating modes was examined. The system was optimized by deploying the assistant preheating/precooling approach and over one-year period monitoring showed that the seasonal Coefficient of Performance(COP) of the GSHPS was 4.12 in winter and 5.01 in summer. These COP values are higher than that of the conventional GSHPS. Thus, this proposed strategy could be an efficient way to improve the thermal performance of GSHPS.

Application and development of ground source heat pump technology in China

Ground source heat pumps (GSHPs) are one of the renewable energy technologies with features of high efficiency, energy saving, economic feasibility and environmental protection. In China, GSHPs have been widely used for building heating and cooling in recent years, and have shown great potential for future energy development. This paper summarizes the classification, development history, and use status of shallow GSHPs. Several typical engineering cases of GSHP technology are also specified and analyzed. Finally, promising development trends and some advanced technologies are illustrated.

Numerical and experimental studies of hydraulic noise induced by surface dipole sources in a centrifugal pump

The influences of the four different surface dipole sources in a centrifugal pump on the acoustic calculating accuracy are studied in this paper, by using the CFD combined with the Lighthill acoustic analogy methods. Firstly, the unsteady flow in the pump is solved based on the large eddy simulation method and the pressure pulsations on the four different surfaces are obtained. The four surfaces include the volute surface, the discharge pipe surface, the inner surface of the pump cavity, and the interfaces between the impeller and the stationary parts as well as the outer surface of the impeller. Then, the software Sysnoise is employed to interpolate the pressure fluctuations onto the corresponding surfaces of the acoustic model. The Fast Fourier Transform with a Hanning window is used to analyze the pressure fluctuations and transform them into the surface dipole sources. The direct boundary element method is applied to calculate the noise radiated from the dipole sources. And the predicted sound pressure level is compared with the experimental data. The results show that the pressure fluctuations on the discharge pipe surface and the outer surface of the impeller have little effect on the acoustic simulation results. The pressure pulsations on the inner surface of the pump cavity play an important role in the internal flow and the acoustic simulation. The acoustic calculating error can be reduced by about 7% through considering the effect of the pump cavity. The sound pressure distributions show that the sound pressure level increases with the growing flow rate, with the largest magnitude at the tongue zone.

Numerical simulation of super-continuum laser propagation in turbulent atmosphere

Considering the atmospheric extinction and turbulence effects,we investigate the propagation performances of supercontinuum laser sources in atmospheric turbulence statistically by using the numerical simulation method,and the differences in propagation properties between the super-continuum(SC)laser and its pump laser are also analyzed.It is found that the propagation characteristics of super-continuum laser are almost similar to those of the pump laser.The degradation of source coherence degree may cause the relative beam spreading and scintillation indexes to decrease at different propagation distances or different turbulence strengths.The root-mean-square value of beam wandering is insensitive to the variation of source correlation length,and less aperture averaging occurs when the laser source becomes less coherent.Additionally,from the point of view of beam wandering,the SC laser has no advantage over the pump laser.Although the pump laser can bring about a bigger aperture average,the SC laser has a lower scintillation which may be due to the multiple wavelength homogenization effects on intensity fluctuations.This would be the most important virtue of the SC laser that can be utilized to improve the performance of laser engineering.

Comparative Analysis of Two Energy-Efficient Technologies Used in the Shanghai Tower

Climate change continues to affect the lives of individuals across the world, creating a rise in demand for new technologies that can slow down the impacts of climate change. Shanghai, one of the largest cities in the world, has one of the highest carbon emission levels. In recent years, the research and development of energy-efficient technologies have gained more and more attention. The Shanghai Tower is a pioneer in green building design and a prominent example of Shanghai’s efforts towards low-carbon city development. In this paper, two technologies within the Shanghai Tower—ground source heat pumps (GSHP) and double skin facades (DSF)—will be analyzed. The paper will consist of firstly an investigation of the principles of the technologies, and then analysis, evaluation, and comparison of their respective characteristics. While both GSHP and DSF are used for sustainable purposes, the effectiveness of technologies depends on what environment the technology is used in and what purpose they serve. The evaluation of GSHP and DSF will be based on their performances under Shanghai’s climate and whether they contribute to the purposes of the Shanghai Tower.

Design and analysis of a novel dual source vapor injection heat pump using exhaust and ambient air

A novel dual source vapor injection heat pump(DSVIHP)using exhaust and ambient air is proposed.The air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator.A vapor injection(VI)compressor of two inlets is connected with the low and medium pressure evaporators.It’s first time that a VI compressor is employed to recover the ventilation heat.The system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste heat.Fundamentals of the proposed DSVIHP are illustrated.Mathematical models are built.Both energetic and exergetic analyses are carried out under variable conditions.The results indicate that the DSVIHP has superior thermodynamic performance.The superiority is more appreciable at a lower ambient temperature.It has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3%and 23.2%respectively at an ambient temperature of-10°C and condensation temperature of 45°C.The waste heat recovery ratio from the exhaust air is more than 100%.The novel DSVIHP has great potential in the cold climate area application.

Generation of Interstellar Class Ⅱ 7_2-8_1A^+ and 7_2-8_1A^-Methanol Masers

New methanol maser lines at 72 → 63A^-（86.6 GHz） and 72 → 63A^＋（86.9 GHz） together with two candidate methanol maser lines at 72 → 81A-（80.99GHz） and 72→81A^＋（111.29GHz） have been detected in W3（OH）. We use a pumping mechanism, i.e., methanol masers without population inversion, to explain the formation of weak methanol masers of 72 → 81A^＋ and 72→ 81A^-. We explain well why the line-shape of the transition 72 → 81A^＋ is not typical. A similar argument can be applied to the A-type level system 72A^-, 63A^- and 81A^-, as well as to the 72 → 81A^- 80.99 GHz masers.

Numerical Simulation of Mid-Deep Buried Casing Heat Exchanger and its Heating System Application

Although the mid-deep ground source heat pump could be more excellent for heating compared to other heat pumps,whose well depth is usually 2000-4000 m underground,the references on it is far fewer than the market demand to apply it more.To facility the application of the mid-deep ground source heat pump and the heating problem solution to transform the coal-boiler used in a Logistics Park of Lanzhou city,firstly,this paper established a three-dimensional numerical model of mid-deep ground source heat exchanger,and analyzed the effects of well flow,diameter and depth on heat pump performance with the help of Fluent software.And then,the heating source renovation to mid-deep ground source heat pump was carried out and the test funded by the local government was followed from February 1,2018 to March 31,2018.It is concluded that the numerical analysis is reasonable and the heating system is effective and reliable,whose average COP(coefficient of performance)and cumulative power consumption is 3.47 and 67727 kWh respectively during the test period.

Numercial analysis on the thermal performance of capillary heat exchange system in metro running tunnel

During the operation of the capillary heat exchange system in the metro tunnel,the pipe length,pipe spacing and air velocity have different effects on the heat transfer effect and show certain rules.Taking Kunming as an example,a single-factor analysis method was used to establish multiple-capillary model,and the variation of different influencing factors in the heat transfer process was obtained.On this basis,a single-capillary model was established to analyze the thermal interference variation of the pipe spacing between the two models.Under the condition of ensuring the capillary outlet water temperature and heat flux,the relevant parameters of the capillary heat exchanger were optimized.The results show that the pipe length of the capillary heat exchanger should be kept within 3-5 m,the pipe spacing is maintained at 20-30 mm,and the capillary heat exchanger of each set can be operated in parallel to ensure that heat exchanger have better heat transfer performance.During the system stop running,the air velocity in winter and summer has different effects on the recovery of surrounding rock.