Gas Engine-driven Heat Pump Research Articles

Experimental research on the property of water source gas engine-driven heat pump system with chilled and hot water in summer

The present work aims to explore a new energy supply way for users with chilled and hot water demand in summer. To achieve this goal, a water source gas engine-driven heat pump (WSGHP) system with R134a was developed. The WSGHP system used evaporator to product chilled water, at the same time, made use of condensing heat and engine waste heat to product domestic hot water. The impact of engine speed, evaporator/condenser water inlet temperature on the gas consumption, cooling capacity, heat recovery, and system energy efficiency had been researched in detail. Testing results indicated that the WSGHP system was able to perform stably under various conditions. The primary energy ratio without heat recovery (PER1) of system is from 0.61 to 0.85. However, when the condensing heat and engine waste heat are recovery, its primary energy ratio (PER2) is 2.09–2.34. The cooling capacity, condensing heat and engine waste heat account for 31.5%, 40.0%, and 28.5% of the total capacity of the system, respectively. Therefore, the new energy supply system has great significance to the development of energy-saving and environmental protection.

A Study of Hybrid-Power Gas Engine-Driven Heat Pump Control Strategy Based on Instantaneous Optimization

The control strategy for a coaxial parallel hybrid-power gas engine-driven heat pump system is studied based on instantaneous optimization, aiming at minimizing the equivalent energy consumption. The system includes two main subsystems, drive subsystem and heat pump subsystem. Continuously variable transmission (CVT) is applied to combine the two subsystems for a continuous transmission ratio adjustment. The steady-state models of components of the two subsystems are established, and based on which equivalent energy consumption function is proposed. Meanwhile, a penalty factor is introduced into study of battery to maintain SOC in range of 0.2 to 0.8, where the internal resistance is relatively small. Then computational simulation work is performed on Simulink platform. Result shows that battery SOC runs stable between 0.49∼0.66 and equivalent energy consumption is 10.4% lower than that of system with multi-stage gear ratios.

Experimental study on the gas engine speed control and heating performance of a gas Engine-driven heat pump

ABSTRACT The gas engine-driven heat pump (GEHP) system is an energy saving device for heating, cooling or hot water supply. As the power source of the system, the performance of gas engine speed control directly has a significant impact on the system stability and efficient operation. However, gas engine is typically a nonlinear dynamical system and easily disturbed by the load fluctuation, which increases the difficulty of control of gas engine speed. Therefore, a gas engine speed control strategy is proposed for a GEHP system. Aiming at achieving this objective, a test facility is developed and an engine speed controller is designed according to the characteristics of the gas engine and the GEHP system. Then the engine speed controller is applied to the GEHP system and experiments are performed under different conditions: engine speed setting control and anti-disturbance control. The experimental results show that it costs less than 40 s to make the engine speed steady without overshoot when engine speed setting changes. When the disturbances of superheat change occur, the error (accuracy) of the engine speed is controlled within ± 50 rpm. The engine speed control strategy can not only guarantee the stable operation but also satisfy the capacity adjustment performance of the GEHP system. Finally, performance characteristics of the GEHP are characterized by heating capacity and primary energy ratio (PER). The results indicate that engine speed is an important factor which influences the performance of the GEHP. The heating capacity increases with the increase of engine rotational speed, while PER of the GEHP decreases. In terms of energy saving, the GEHP system should operate at lower engine speed in the case of satisfying the system load.

The influence of building using function on the operating characteristics of the gas engine driven heat pump with energy storage system (ESGEHPs)

The objective of this study is to improve the applicability and efficiency of the gas engine driven heat pump with energy storage system when supplying heating and cooling to the different types of buildings. The physical models of four types of buildings, including residential, hotel, office and university building, were sampled and simulated by the DesignBuilder software using the weather data of typical weather year in Tianjin. The building cooling and heating load characteristics of the typical air-conditioning day (17/07/2016) and the typical heating day (07/01/2017) was chosen as the research data. It was found that the four types of buildings had different load demand due to the different function and characteristics of the buildings. The control strategy of the gas engine driven heat pump with energy storage system with four modes, such as Mode L, Mode P, Mode F and Mode O, was developed to meet the various building heating and cooling load demand. The simulation results showed that the annual primary energy ratio of the gas engine driven heat pump with energy storage system is about 21.4% (residential), 35.2% (hotel), 23% (office)and 26.6% (university) higher than traditional gas engine heat pump system. And a compared experiment was given, which demonstrated that the simulation relative errors of the university building cooling load, the cooling/heating capacity of the gas engine driven heat pump with energy storage system, fuel-consumption and primary energy ratio were lower than 12%, except the heating load with the relative error of 35.6%. From these results, the gas engine driven heat pump with energy storage system could be used in different types of buildings with a more stable operation characteristic, higher primary energy ratio and more suitable performance. The results presented in this paper is of some reference basis for optimizing the gas engine driven heat pump with energy storage system and developing a new route for raising cooling/heating quality, energy saving and consumption reducing.

Dynamic optimal control and economic analysis of a coaxial parallel-type hybrid power gas engine-driven heat pump

HPGHP (Hybrid power gas engine-driven heat pump) is a novel air conditioning system, which combines traditional heat pump with hybrid technology. In this paper, the transmission ratio of a coaxial parallel-type hybrid power gas engine-driven heat pump is firstly optimized considering the differences between refrigeration and heating conditions, based on the instantaneous optimization control strategy of engine optimal torque curve. The results of the optimization are as follows: under the high, medium and low load conditions, the ratio is 2.4, 1.5 and 1.3 respectively under cooling conditions and 2.7, 1.7 and 1.4 respectively under heating conditions. Secondly, the related performance parameters of HPGHP are analyzed with particularly established simulation model including SOC and SOH parameters of the battery. The experimental and simulative researches indicate that: After a simulation cycle where the load is evenly distributed within 3600 s, the battery SOC value increased from 55% to 59.85%, SOH value from 1 to 99.942%. The average thermal efficiency in the three modes is 0.26664, 0.27594 and 0.27831, respectively. Compared with the results of Wang et al., it has been improved by 1.49%, 6.47% and 4.85%. Finally, an economic objective function including gas consumption and battery loss is introduced and the overall operating costs of HPGHP and GHP systems are analyzed and compared. Furthermore, considering the similarity between the HPGHP system and GEHP system, the PER is used as the index to compare the two systems. The comparison show that the average PER of HPGHP is about 12.1% higher than that of GHP.

Start-up behaviour of a combined air-conditioning system in cooling and heating operating modes

The energy demand of the commercial building sector is largely for cooling and heating and will eventually result in energy and environmental crises; therefore, enhancing the performance of the cooling and heating systems used in buildings is paramount. In response to this need, focus was set on the gas engine-driven heat pump-combined system (GHPC)—consisting of a gas engine, single-stage vapour compression system, and single-effect absorption system— that saves more energy as compared to a conventional gas engine-driven heat pump. However, so far, only the performance and transient characteristics of a fabricated GHPC have been investigated. Therefore, to ascertain the characteristics of the GHPC start-up dynamics under unsteady state operations so as to achieve efficient and stable start-up operation, experiments and simulations were attempted in this study. The transient behaviour from the start-up of this combined system in cooling and heating operating modes was also scrutinized. Accordingly, it was found that simulation results agreed well with experimental data. It was concluded that there were no large delayed responses in the absorption system during start-up operation when start-up of the absorption system is considered based on the system cooling capacity response after the solution pump starts.

Experimental investigation of a gas engine-driven heat pump system for cooling and heating operation

The present work aimed at evaluating the performance of a gas engine driven heat pump (GEHP) for cooling and hot water supply. A test prototype working with R134a was built, and the cooling performance with hot water supply were experimented in a range of evaporator water inlet temperature from 12 °C to 22 °C, ambient air temperature from 24.2 °C to 37 °C, and gas engine speeds from 1400 rpm to 2000 rpm. The results show that the effects of evaporator water inlet temperature and gas engine speed on the system performance are more significant than those of ambient air temperature. Average hot water outlet temperatures between 40.7 °C and 61.7 °C are obtained over the considered range of the external operating parameters and this met the temperature demand of domestic water for shaving, residential dish washing, and laundry. Moreover, the primary energy ratio (PER2) of GEHP system is between 1.14 and 1.45 with waste heat recovery.

Thermal modeling and experimental research of a gas engine-driven heat pump in variable condition

In order to analyze the influence of various factors on the system performance of the gas engine-driven heat pump system with waste heat recovery, theoretical model of a gas engine-driven heat pump is conducted in this paper. The thermal modeling of the gas engine-driven heat pump including both the heat pump and the gas engine system was performed and the system performances under different operating parameters were simulated. The results show that the engine speed and the outdoor air temperature affected the system performance significantly. With the engine speed increasing from 1400rpm to 2000rpm, the heating capacity increased by 26.9% while system primary energy ratio (PER) decreased by 17.6% for the air temperature of 10°C. When the outdoor air temperature reduced from 10 to 2°C, the heat capacity reduced by 14.6% but the system PER decreased by 11.8% with the engine speed of 1800rpm. The water inlet temperature act insignificantly on heating capacity, while it had some influence on the system PER. With the water inlet temperature increasing from 38 to 44°C, the system PER decreased by 5.7% and 4.4% for the outdoor air temperature of 10 and 2°C, respectively. The experimental test is also carried out to validate the simulation models. The comparison of modeling results and the experimental measured values for various amounts of the heating capacity, PER, waste heat recovery and the percentage of heat recovery showed 4.8%, 4.6%, 6.7% and 5.6% average difference percentage, which indicated an accepted agreement. From the perspective of energy savings, the gas engine-driven heat pump should be operated with engine speed as low as possible in the case of meeting the heating requirements.

Energy-saving analysis of a hybrid power-driven heat pump system

A gas engine-driven heat pump (GEHP) is traditionally applied for both heating and cooling; however, the cooling performance may be worse than that of an electric heat pump (EHP) because of the waste heat rejection of the gas engine. To improve the system performance of the air source heat pump for the entire year running, a hybrid power-driven heat pump (HPHP) system is proposed, in which the heat pump is driven by a gas engine for heating and by electricity for cooling. The mathematical model of the HPHP system is established, and the performance of the HPHP system is compared with those of GEHP and EHP. It is demonstrated that the primary energy ratio (PER) of the HPHP is 28.5–51.2% higher than that of the GEHP for cooling and 15.8–25.3% higher than that of the EHP for heating. Compared to the GEHP and the EHP, the energy saving ratio of the HPHP is 10.9% and 14.4% in Beijing, respectively, and the corresponding value is 18.5% and 7.3% in Shanghai, respectively. These results highlight the great application potential of the HPHP system for both heating and cooling.

The multi-goal optimal analysis of stand-alone gas engine heat pump system with energy storage (ESGEHP) system

Gas-engine driven heat pump could avoid energy loss in the process of generation, transmission and distribution, and effectively reduce the electric power load at the peak time in summer. In the present study, a novel stand-alone gas engine heat pump system with energy storage is put forward, which combined with the energy storage system and the autonomous power supply system. The annual performance optimization model of the gas engine heat pump system with energy storage system is proposed, which is calculated based on APSO algorithm. The simulation results were well agreed with experimental data, the average difference is 8.9%, 9.63% and 21.7% for the annual primary energy ratio of heating, cooling, transitional season, respectively. Based on the simulation results, the autonomous generating capacity E and the speed of engine n have high effect on the objective function, and the ratio of electricity to heat/cool/domestic hot water should be no greater than 0.1. The annual primary energy ratio of the gas engine heat pump system with energy storage system in heating, cooling and transitional season was increased by 6.11, 19.11% and 34.83% compared with the gas-engine driven heat pump system, respectively. The gas engine heat pump system with energy storage system can be used indifferent climate regions and buildings, which could provide a more stable work mode and higher annual primary energy ratio than the gas-engine driven heat pump system with a little energy loss.

Optimization of the waste heat reclaim system in Hybrid-power Gas Engine-driven Heat Pump

The coaxial parallel-type hybrid power gas engine-driven heat pump (HPGHP) system combines hybrid power technology with gas engine-driven heat pump, which can be divided into three parts: the power-driven system, the heat pump system and the heat reclaim system. In this paper, on the basis of HPGHP system experiments, the mode of the heat reclaim system is established, then the engine waste heat reclaim coefficient of flue gas waste heat, cylinder liner waste heat and total heat is researched. The results show that the waste heat reclaim coefficient of cylinder liner waste heat is significantly higher than the flue gas waste heat. In addition, to evaluate the thermal performance and fuel economy of flue gas heat exchanger, the annual net income of unit flue gas heat reclaim model is established. Finally, the heat transfer area of flue gas heat exchanger is optimized. The results show that when NTU is approximately 0.6, the annual net income of per unit flue gas heat reclaim reaches a maximum value, this moment, the economic optimum heat transfer area is 1.79 m2 approximately.

Experimental study on cooling performance and energy saving of gas engine-driven heat pump system with evaporative condenser

The gas engine-driven heat pump (GEHP) is widely utilized to the process of cooling, heating or food drying. Aiming at improving the coefficient of performance (COP), primary energy ratio (PER) and energy saving of GEHP, a GEHP system with evaporative condenser was developed and the cooling performances were experimented over a wide range of ambient air temperature (30–36°C), evaporative condenser air velocity (2.2–3.9m/s) and gas engine speeds (1200–2200rpm). Experimental results showed that the cooling capacity and PER of the GEHP system with evaporative condenser increased as the increasing of evaporative condenser air velocity and decreasing of ambient air temperature. The increasing and decreasing extents of cooling capacity and PER were 12.1%, 4.8% and 8.2%, 9.0%, respectively. However, the gas engine energy consumption and gas engine waste heat decreased with the increasing of evaporative air velocity and decreasing of ambient air temperature. Meanwhile, the cooling capacity, gas engine energy consumption, gas engine waste heat increased with increasing of gas engine speed, and the increase amplitude was 75.64%, 153.2% and 153.3%, respectively. The maximum value of PER of GEHP system with evaporative condenser was 1.55, and the waste heat recovered from gas engine was more than 55% of gas engine energy consumption.The energy saving and emission saving of the GEHP with evaporative condenser were also analyzed, the PER savings of GEHP system with evaporative condenser compared to conventional air-cooled condenser were 28.1%. Furthermore, compared to the GEHP with air-cooled condenser, the primary energy saving and CO2 emissions saving of GHEP with evaporative condenser were 16.3% and 8.8%. The results displayed an excellent energy-saving feature.

Modeling and Optimization of a Hybrid-power Gas Engine-driven Heat Pump

Based on the coaxial HPGHP system experiments, the mathematical model of the various components of the coaxial HPGHP system is established to research the matching relations between the drive system and the load demand of the compressor. This paper establishes the thermal efficiency of the engine model based on load rate, to maintain the thermal efficiency always be above 0.25, combined with the thermal efficiency map of the engine, the best economic zone of engine operation is determined. Finally, Torque optimization model of the coaxial HPGHP system was proposed, the transmission ratio of the HPGHP system was optimized and mode control strategy of the coaxial HPGHP system was determined. Simulation results show the thermal efficiency of the HPGHP system can be always been guaranteed above 0.25 and the transmission ratios are respectively 2.9, 1.8 and 1.4 in three different load demand range.

Energy Management of a Hybrid-Power Gas Engine-Driven Heat Pump

The hybrid-power gas engine-driven heat pump (HPGHP) combines hybrid power technology with a gas engine heat pump. The engine in the power system is capable of operating constantly with high thermal efficiency and low emissions during different operating modes. In this paper, the mathematical models of various components is established, including the engine thermal efficiency map and the motor efficiency map. The comprehensive charging/discharging efficiency model and energy management optimization strategy model which is proposed to maximize the efficiency of instantaneous HPGHP system are established. Then, different charging/discharging torque limits are obtained. Finally, a novel gas engine economical zone control strategy which combined with the SOC of battery in real time is put forward. The main operating parameters of HPGHP system under energy management are simulated by Matlab/Simulink and validated by experimental data, such as engine and motor operating torque, fuel consumption rate and comprehensive efficiency, etc. The results show that during 3600 s’ run-time, the SOC value of battery packs varies between 0.58 and 0.705, the fuel consumption rate reaches minimum values of approximately 291.3 g/(kW h) when the compressor speed is nearly 1550 rpm in mode D, the engine thermal efficiency and comprehensive efficiency reach maximum values of approximately 0.2727 and 0.2648 when the compressor speed is 1575 rpm and 1475 rpm, respectively, in mode D. In general, the motor efficiency can be maintained above 0.85 in either mode.

천연가스 열량 변화에 따른 GHP 엔진의 성능 및 배출가스 특성

가스엔진구동 히트펌프(GHP : Gas Engine Driven Heat Pump)의 연료인 천연가스의 열량이 감소함에 따라 국내에서 생산되는 GHP에 미치는 영향을 평가하였다. 저열량가스(<TEX>$9,800kcal/Nm^3$</TEX>)를 연료로 사용하여 엔진 단체 실험 및 GHP 현장평가를 실시한 결과 약간의 출력감소가 확인되었으나 시동성, 운전안정성, 배출가스 특성 등은 거의 변화가 없음을 확인하였다. 따라서 천연가스 열량이 <TEX>$9,800kcal/Nm^3$</TEX>까지 감소하여도 별도의 조정없이 GHP가 정상운전될 수 있을 것으로 판단된다. In general, natural gas is used as GHP(Gas Engine Driven Heat Pump) fuel. On this study, the influences of different natural gas heating value on GHP were evaluated. As a result of engine test & field test using low heating value gas(<TEX>$9,800kcal/Nm^3$</TEX>) as fuel, the engine power was reduced slightly, however the performance of start-up, the stability of operation and the characteristics of emission gas were almost similar. So it is considered that the normal operation of GHP is possible without any tuning when the low heating value(<TEX>$9,800kcal/Nm^3$</TEX>) of natural gas was used as fuel.

Experimental Study of the Gas Engine Driven Heat Pump with Engine Heat Recovery

Gas engine driven heat pumps (GEHPs) represent one of practical solutions to effectively utilize fossil fuel energy and reduce environmental pollution. In this paper, the performance characteristics of the GEHP were investigated experimentally with engine heat recovery. A GEHP test facility was set up for this purpose. The effects of several important factors including engine speed, ambient temperature, condenser water flow rate, and condenser water inlet temperature on the system performance were studied over a wide range of operating conditions. The results showed that the engine waste heat accounted for about 40–50% of the total heat capacity over the studied operating conditions. It also showed that engine speed and ambient temperature had significant effects on the GEHP performance. The coefficient of performance (COP) and the primary energy ratio (PER) decreased by 14% and 12%, respectively, as engine speed increased from 1400 rpm to 2000 rpm. On the other hand, the COP and PER of the system increased by 22% and 16%, respectively, with the ambient temperature increasing from 3 to 12°C. Furthermore, it was demonstrated that the condenser water flow rate and condenser water inlet temperature had little influence on the COP of the heat pump and the PER of the GEHP system.

Experiments and thermal modeling on hybrid energy supply system of gas engine heat pumps and organic Rankine cycle

This paper presents a hybrid energy supply system, which is composed of two subsystems (gas engine-driven heat pump system (GEHP) and organic Rankine cycle system (ORC)) and three major thermodynamic cycles (the vapor compression refrigeration cycle, the internal combustion gas engine cycle and ORC). In order to convert the low-grade gas engine waste heat into high-grade electricity, the ORC system is built up using R245fa, R152a and R123 as working fluids, and the ORC thermal model is also developed. Meanwhile, experiments of GHEPs in cooling mode are conducted, and several factors which influence the cooling performance are also discussed. The results indicate that the cooling capacity, gas engine energy consumption, gas engine waste heat increase with increasing of gas engine speed and decrease with decreasing of evaporator water inlet temperature. The waste heat recovered from gas engine is more than 55% of gas engine energy consumption. F6urthermore, R123 in ORC system yields the highest thermal and exergy efficiency of 11.84% and 54.24%, respectively. Although, thermal and exergy efficiency of R245fa is 11.42% and 52.25% lower than that of R123, its environmental performance exhibits favorable utilization for ORC using gas engine waste heat as low-grade heat source.

Performance analysis, model development and validation with experimental data of an ICE-based micro-CCHP system

The ICE technology applied to micro-CHP is a mature technology, with certain equipment established in the market. The integration of chillers in micro-cogeneration systems can be used to develop micro-CCHP systems with high overall efficiencies and high potential for integration in buildings. Studies of the behavior of these machines are necessary to develop models that simulate the micro-CCHP system under different weather conditions in different building configurations. This paper presents a micro-CCHP with heat recovery based on a Honda gas engine. The system incorporates a heat pump to meet the need for air conditioning. To analyze the behavior of the tri-generation system and its capabilities, a fully functional prototype is built and tested in the laboratory under different operating modes. The obtained results from the experimental data reveal that the maximum electrical efficiency is 7.63% and it is obtained when the heat pump is off and engine is operating at low speed. The higher performance of the gas engine driven heat pump is 10.79% and it is achieved when the engine is running at high speed. A model of the system is developed using TRNSYS software components and validated using the experimental data obtained during testing of various operating modes. The main contribution of this paper is focused on the applied methodology of tests, model, and validation through simulation. The proposed methodology includes experimental validation of the CCHP model using the TRNSYS energy simulation software. The features of this model make it appropriate for use as a stand-alone system in building simulations to produce electricity, DWH, heating and cooling.

Simulation Analysis of Primary Energy Ratio for Air-Source Gas Engine-Driven Heat Pump

Based on the simulation of the air conditioning construction dynamic load and simulation calculation of air-source gas engine-driven heat pump (GEHP), the air-source GEHP air conditioning in winter, summer and the annual primary energy ratio are analyzed in simulation with the combination of a hotel building in Tianjin. Firstly, DeST software is used to simulate all-year hourly air conditioning load of the building. Then air-source GEHP simulation model [1] is used to calculate the annual hourly gas consumption and the amount of GEHP's gas consumption in winter, summer and a total year afterwards can be got. At the same time, by the analysis of waste heat recovery of gas engine-driven, primary energy ratio for air-source GEHP in Tianjin is given under the different waste heat recovery of winter, summer and the annual.

Evaluation method of gas engine-driven heat pump water heater under the working condition of summer

Abstract As the current evaluation methods of gas engine-driven heat pump systems (GEHPs), primary energy ratio (PER) is incapable to evaluate the seasonal performance of gas engine-driven heat pump water heater (GEHPWH), and seasonal primary energy ratio (SPER) is too complex in procedures. An evaluation method for seasonal performance of GEHPWH should be proposed, which is both simple and accurate. This paper presents a new evaluation method named integrated primary energy ratio (IPER) based on PER and SPER. In order to test the validity of the evaluation result, experimental studies about seasonal performance of GEHPWH have been carried under the working condition of summer. Experimental results indicated that the calculation result of IPER is relatively accurate compared with the calculation result of SPER, while the experimental and calculation procedures of IPER are much simpler than that of SPER. The seasonal performance of GEHPWH calculated with SPER is 2.09 in summer, and the IPER value of GEHPWH in the same condition is 2.01, the error compared with SPER is only 3.7%.