Gas Engine-driven Heat Pump Research Articles

A REVIEW on PRIMARY ENERGY RATIO VALUES of GAS ENGINE DRIVEN HEAT PUMP SYSTEMS

This study reviews the primary energy ratio values of gas engine driven heat pump systems in order to compare gas engine driven heat pump systems among themselves or with heat pump systems using different energy sources in terms of efficiency values. A comprehensive literature review of studies investigating primary energy rates of gas-driven heat pump systems have been presented. The primary energy ratios obtained in the studies on gas driven heat pump systems were determined and tabulated. In addition, waste heat recovery rates in these systems were also investigated. Studies in the relevant field are grouped as experimental and theoretical. Additionally, the differences in the examined system structures are stated and primary energy ratios are presented. Primary energy rates of systems with and without heat recovery were examined. There is no compilation study on the subject in the literature. The calculation methodology used and the obtained values for calculating the primary energy rates of gas-driven heat pumps are presented. Thus, the energy efficiency and environmental evaluations of the examined systems are presented in the light of the literature. In addition, which refrigerants were used in the studies conducted in the literature are presented. Recommendations are provided on choosing alternative and sustainable refrigerants.

Demand side management optimization and energy labeling of multi-purpose buildings

A multi-purpose building with different applications such as residential, office, cultural, restaurant, parking, etc. is analyzed in this research. The facilities in many multi-purpose buildings in developing countries are considered having old energy systems with high energy consumption. Application for national energy labeling require optimizing the energy consumption. However, many such buildings in Iran are not awarded the above-mentioned label. The present study aims to assess a multi-purpose building which is not able to get standard energy label with existing situation. To reduce energy consumption in such buildings, solutions such as applying phase-change materials (PCM) in exterior walls, installation of photovoltaics (PV), employing building energy management system (BEMS), and switching the central system to gas engine-driven heat pump (GEHP) were analyzed. The reduction of energy consumption due to PCM, PV, BEMS, and GEHP solutions were 2, 6, 23, and 63%, respectively. The use of PCM, PV, and BEMS failed to enabling the building to receive energy label. Instead, the E category energy label was received only by switching the central heating system to the GEHP system. The payback period for switching the facilities to GEHP system lasted 7.5 years. This method of energy labeling can be used for all of the past multi-purpose Buildings.

Modeling and experimental investigation on a gas engine-driven heat pump for space-heating and sanitary hot water

Utilization of gas engine-driven heat pumps (GEHP) can reduce the heavy loads on the power grid when electric heat pumps operate during the heating season. This study is to examine the performance of GEHP as a water heater with different engine speeds and water flow rates providing space-heating and sanitary hot water. When the engine speed rises from 1400 rpm to 1900 rpm, the temperature rise of water increases by 37% from 25.7 °C to 35.3 °C. Moreover, the system heat capacity rises from 71.8 kW to 97.7 kW with an increase of 36%, while the COP decreases from 3.6 to 3.0. As the inlet water flow rate an increase from 2.5 m3/h to 4.0 m3/h, the temperature rise decreases from 44.3 °C to 24.1 °C, with decreasing heat capacity from 128.8 kW to 112.1 kW. Additionally, the primary energy ratio (PER) initially increases from 1.46 to 1.50 at the engine speed of 1800 rpm, followed by a slight decrease to 1.48 when the engine speed reaches 1900 rpm. With an increasing water flow rate, the PER achieves its highest value of 1.64 at 3 m3/h and its lowest value of 1.49 at 3.5 m3/h.

Study on performance of a gas engine-driven heat pump system with R410A for heating and domestic hot water applications

Traditional gas engine-driven heat pump (GHP) systems were switched off in the transitional season, and the engine waste heat could no longer be used for producing domestic hot water. Most studies on GHP systems used piston compressors with low efficiency, and the refrigerants used were R134a or R407C. This paper presents an innovative GHP system using open scroll compressors with R410A which can be used throughout the year. The novel GHP system can be switched freely between heating mode-H, which produced heating water combined with domestic hot water, and heating mode-D which only produced domestic hot water. In these two heating modes, the effects of different condenser water outlet temperatures (tw,out1), domestic hot water outlet temperatures (tw,out2), engine speeds (Neng), and total domestic hot water outlet temperatures (tw,out3) on performance of the GHP system for heating and domestic hot water applications were experimentally investigated. The results show that tw,out1 and tw,out3 have greater effect on primary energy ratio (PER), Neng has significantly larger effect on heating capacity and the recovered waste heat, whereas tw,out2 has little effect on the comprehensive performance. The change between heating mode-H and heating mode-D hardly affects the system heating performance. For the experiments, the waste heat recovery rates are between 42.05 % and 61.08 %. The total PER of the GHP system ranges from 1.179 to 1.453 without waste heat recovery, while it ranges from 1.521 to 1.834 when the engine waste heat is recovered. It indicates that the total PER can be significantly improved by recovering the engine waste heat.

Study on performance of a water-source gas engine-driven heat pump system for combined cooling and heating supply

Study on performance of a water-source gas engine-driven heat pump system for combined cooling and heating supply

Modelling and performance analysis of power system in gas engine-driven heat pump

The gas engine-driven heat pump (GHP) is an energy-saving and environmentally friendly technology. In previous studies, there were few dynamic quantitative analyses of gas engines’ exergy efficiency (ηex,e) and waste heat recovery (Qrec), which are essential but not easy to achieve. This paper establishes the multivariate regression equations of related physical quantities according to the manufacturer or experimental data. Based on the above, the effect of the engine’s two-dimensional (2-D) factors on thermal efficiency (ηe), ηex,e, and Qrec are analyzed, respectively. Since the scroll compressor manufacturer could not provide data and selection software, a general modelling method was proposed based on experimental data and gain the quantitative analysis of mechanical (ηm) and exergy efficiency, which is also less in previous studies but essential. In addition, the primary performance of GHP is also analyzed through the coupled model of the power system. The main results show that: ηe and Qrec are positively correlated with the engine’s load, while ηex,e is the contrary. Using a higher low heating value (LHV) gas can increase ηe and Qrec by 3.38 % and 1.12 kW, respectively, compared with a lower one. The ηex,sc and ηm of the compressor are positively correlated with the heat pump load, varying in 55.51–77.12 % and 68.20–97.52 %, respectively. In summary, the power system model established in this paper can supplement the lack of quantitative analysis of main parameters in the previous GHP, and the modelling method of the compressor is also generally applicable to other heat pump systems.

가스히트펌프를 이용한 온실 난방 및 배가스 탄산시비 시스템의 경제성 및 온실가스 배출 영향 평가

The area of domestic horticulture continuously enlarged and the heating costs also increased to about 30 ~ 40% of the total operating expenses. To enhance the profitability of production, it is increasingly important to estimate the energy costs of greenhouses properly. This study aimed to compare the economic feasibility and the greenhouse gas emission of greenhouse energy systems according to heating methods with different fuel types. The annual power consumption was calculated by using TRNSYS, a commercial Building Energy Simulation(BES) tool. First, the model validation was performed using the experimental data obtained from the greenhouse that uses a gas engine drive heat pump. The results were compared with the reference kerosene heating case (CASE 1), which is widely used in domestic greenhouses. The analysis showed that gas heating case (CASE 2) has reduced total energy costs by 20% and greenhouse gas emissions by 10%. Whereas, the exhaust gas from gas engine driven heat pump can be used as a CO₂ source for enhancing photosynthesis. Lastly. the results from the GHP heating case (CASE 3) showed a 46% reduction in total cost and a 63% reduction in greenhouse gas emissions.

Investigation of the polygeneration system integrated with gas engine-driven heat pump system and CO2 Brayton cycle for waste heat recovery

A gas engine-driven heat pump system could provide cooling and heating, and fully recover the waste heat. The temperature of the waste heat recovered from the gas engine cylinder jacket and exhaust gas was more than 90℃ and 350℃, respectively. The supercritical CO2 Brayton power cycle is considered a promising primary mover of the combined cooling, heating, and power system to potentially provide higher efficiency. Therefore, a polygeneration system composed of gas engine-driven heat pump system and CO2 Brayton cycle was proposed for cooling, heating, and electricity. Experiments of gas engine-driven heat pump system were conducted and the performances were also investigated in the cooling mode. Meanwhile, the thermodynamic performances of the CO2 Brayton cycle were analyzed. The results indicated that the cooling capacity and waste heat increased with the increase of gas engine speed and decreased with the decrease of evaporator water inlet temperature, the primary energy ratio was 1.032, 0.963, and 0.893 at the gas engine speeds of 1260 r/min, 1510 r/min, and 1820 r/min, respectively, and the increasing range was over 43.5 %. In addition, the maximum net power output of CO2 Brayton cycle was 0.97, 1.68, and 2.14 kW, and the gas engine fuel economy was 12.05, 12.35, and 12.10 kg/kWh at the gas engine speeds 1260 r/min, 1510 r/min, and 1820 r/min, respectively. The decreasing range of gas engine fuel with CO2 Brayton cycle system was 8.6 %, 12.3 %, and 12.5 %, respectively.

Performance of a gas engine-driven heat pump system with R410A for cooling and domestic hot water applications

This research work aimed at systematically evaluating the performance of a gas engine-driven heat pump (GHP) system with R410A for cooling and domestic hot water applications. The changes of cooling capacity (Q˙c), heating capacity of waste heat recovery (Q˙h,dom), total effective utilization energy capacity (Q˙all), gas consumption power (Pgas), primary energy ratio (PER), total primary energy ratio (PERall), coefficient of performance (COP), and the growth rate of PER (RPER) were obtained under the conditions of different evaporator water outlet temperatures tw,out1 (5–18 ℃), engine speeds Neng (1200–2000 r/min), and ambient air temperatures Tamb (30–40 ℃). The results show that the energy efficiency can be significantly improved through waste heat recovery. At low Neng, the effect of engine thermal efficiency (ηeng) is greater than that of COP, and PER shows an increasing trend. However, at high Neng, the effect of ηeng is less than COP, and PER tends to decrease. Among the three effect factors, the Neng and Tamb have significantly larger influence on Q˙h,dom, the tw,out1 and Neng have greater influence on Q˙c, and the Tamb and tw,out1 have greater influence on PER. In the experiments, the values of waste heat recovery rate (Rrec,res) are between 59.84 % and 78.81 %, and the values of RPER are between 31.49 % and 60.58 %. It shows that the GHP system has an excellent waste-heat recovery effect, and the PERall is more than 31.49 % higher than that of the traditional GHP system without waste heat recovery.

Experimental investigation on heating performance of a gas engine-driven heat pump system with R410A

• A novel energy-efficient GHP experimental platform is designed based on scroll compressors with R410A. • The effects of five factors on heating performances of the GHP system are systematically investigated. • The mode-4, which only recovers waste heat using the heating water, can improve the heating performance of the GHP system. • In mode-4, the PER is between 0.981 and 2.155, and the rate of waste heat recovery is between 49.12 % and 77.70 %. In this study, the performance characteristics of a gas engine-driven heat pump (GHP) system for heating applications were experimentally investigated. A novel energy-efficient air-source GHP experimental platform was designed based on scroll compressors with R410A. The changes in heating capacity ( Q h ), gas consumption power ( P gas ), compressor power ( P comp ), primary energy ratio ( PER ), and coefficient of performance ( COP ) were obtained under varying conditions of condenser water flow rate G w (6.10–15.25 m 3 /h), water inlet temperature t w,in (24.0–44.2 ℃), engine speed N eng (1200–2400 r/min), and ambient air temperature T amb (−15–7 ℃). The performances of the four heating modes (mode-1 to mode-4) were compared at an ambient air temperature of −20 ℃. The results showed that t w,in , N eng , and T amb had significant influences on heating performance, whereas G w had a slight impact. Compared with other heating modes, mode-4, wherein the recovered waste heat was only transferred to the heating water, could improve the heating performance of the GHP system. In the mode-4 heating experiments, PER was between 0.981 and 2.155, the rate of waste heat recovery was between 49.12 % and 77.70 %, and the engine thermal efficiency was between 27.02 % and 33.24 %.

Economic analysis of gas heat pump in different building applications:A case study in Shanghai

The application of gas engine driven heat pump (GHP) system can improve the peak valley difference of power and gas system and promote the low-carbon utilization of energy system. The energy consumption of GHP system in different types of buildings and especially the coefficient of performance (COP) under partial load rate needs more analysis. In this paper, according to the local meteorological parameters in Shanghai, the COP operation curve of GHP and electric driven heat pump (EHP) units under partial load rate was analyzed. Combined with the load calculation, the annual energy consumption of GHP and EHP units in different types of buildings, and the influence of energy price on economy of GHP system were analyzed. For office buildings and catering buildings, the energy consumption and operating costs of GHP system were slightly lower than those of EHP system, while for hotel buildings, the annual operating costs of GHP were lower than those of EHP only when the winter gas price was 2.39 yuan/m 3 and the summer gas price was 2.19 yuan/m 3 . Therefore, in order to promote the market competitiveness of gas air conditioning, it is necessary to further refine the gas price or charge standard.

Control system and operational characteristics of gas engine-driven heat pump

The control system is an important component of a gas engine-driven heat pump (GHP). Recent studies conducted on GHPs focus on the model construction and optimization, while neglecting the control system. This study proposes an embedded control system to monitor GHP cold–hot water equipment (GHPW). The accuracy of the control system and strategy was verified. Additionally, the operational characteristics of GHPW system based on the control system were discussed through cooling and heating experiments. The experimental results demonstrated that double closed-loop control of the engine speed and evaporator superheat via the main controller ensured stable and accurate outlet water temperature control in the GHPW system. The heating capacity of the heat pump was increased from 42.37 to 75.2 kW in the heating mode with a gradual increase in the engine speed from 1200 to 2400 rpm, while the heating capacity of the experimental system was increased from 56.18 to 105.87 kW. The waste heat recovery of the engine significantly improved the system heating capacity and primary energy ratio (ratio of GEHP heating capacity to natural gas consumption power). Additionally, the GHPW system improved energy saving. The circuits and control strategy proposed in this study are simple and easy to implement. The control system improved the performance of GHPs and reduced the peak power load during summer.

Heating performance of a hybrid power heat pump driven by gas engine and electrical motor

The gas engine-driven heat pump (GEHP) has a higher primary energy ratio (PER) than the electric heat pump (EHP) for heating, but has a lower PER than the EHP for cooling. To exploit the advantages of GEHP and EHP, a heat pump system where the compressor could be driven simultaneously by a gas engine and motor was proposed in the paper. An experimental platform was established to investigate the feasibility and performance of the HPHP system. In addition, numerical models were built for further performance analyses. The results indicate that: (1) Increases in the rotation speed of the compressor and engine power ratio lead to an increase in the total heating capacity. The rotation speed should be adjusted first to meet the required heating load, and then the engine power ratio can be adjusted to achieve better performance; (2) Engine power ratio changes the loads of the engine and motor, thus their efficiencies change, leading to different PERs of the HPHP system. Under different local gas and electricity prices, the engine power ratio can also be adjusted to reach a minimum operating cost; (3) For the case-studied commercial building in Beijing, the annual primary energy consumptions for HPHP, GEHP, and EHP are 94.2, 95.7, and 100.0 kWh/m2, respectively. In addition, HPHP saves operating costs by 17.5 % and 35.1 % compared to GEHP and EHP, respectively, with static payback periods of 2.45 and 1.47 years, even if it is only used for heating in winter.

Modelling and Performance Analysis Based on the Core Components of the Gas Engine-Driven Heat Pump System

Modelling and Performance Analysis Based on the Core Components of the Gas Engine-Driven Heat Pump System

Analysis and optimization of a natural gas multi-stage expansion plant integrated with a gas engine-driven heat pump

Excessive preheating energy consumption is a persistent issue in natural gas expansion power plants. In this paper, a novel system is proposed to solve this problem by using multi-stage expansion and gas engine-driven heat pumps (GHP). A dynamic model based on phase equilibrium theory is established to predict hydrate formation. A control strategy with continuously variable transmission (CVT) for optimizing engine efficiency is investigated through simulation and experiment. Finally, the efficiency and economic performance are compared among GHP, electric heat pump (EHP), and cogeneration (CHP) in a case study. The results show that the engine efficiency of CVT is 4.89% higher than that for multi-level transmission. Compared to single-stage expansion, multi-stage design can reduce preheating temperature by 46%, preheating load by 4.41%, and improve the performance coefficient (COP) of GHP 1.4-fold. The COP of GHP is 33.38% higher than that of EHP, and the primary energy ratio (PER) is 1.81 times that of CHP accordingly. The annual average profit margin for GHP is 1.89 times that of CHP and 7.15 times that of EHP. Thus, the proposed system has significant energy savings and economic advantages.

Research on waste heat recovery from gas engine for auxiliary heating: An emerging operation strategy to gas engine-driven heat pump

Abstract Gas engine-driven heat pump (GEHP) is attracting increasing interest owing to the high heating efficiency and energy-saving. However, the waste heat from engine is mostly used to directly heat domestic hot water. In this study, a new type of waste heat utilization mode of GEHP was proposed: auxiliary heating. The heating capacity, gas consumption, waste heat recovery and compression ratio of water-source GEHP system with waste heat auxiliary heating mode was studied. In addition, the effects of two utilization modes of engine waste heat domestic hot water (mode Ⅰ) and auxiliary heating (mode Ⅱ) on the thermodynamic parameters were compared. The results indicated that the system efficiency was decrease with engine speed. Even in high speed operation, the primary energy efficiency (PER) of the system was more than 1.55. Under the same range of condenser water inlet temperature, the COP of mode Ⅰ was in the range of 4.71–4.95, and that of mode Ⅱ was in the range of 5.17–5.67. The energy saving and emission saving were also researched. Compared with mode Ⅰ, mode Ⅱ had higher efficiency and less pollution to the environment.

Experimental investigation on cooling performance and optimal superheat of water source gas engine-driven heat pump system

To realize the stability and efficiency of the gas engine-driven heat pump, the cooling performance of system are studied. In this paper, the effects of gas engine and superheat (△Tsh) on system refrigerating capacity, refrigerant mass flow rate, gas consumption, compressor ratio, and system efficiency were researched. Then, taking the speed as the variable parameter, the optimal △Tsh in different working conditions were analyzed. The results showed that high speed is not conducive to the energy-saving operation of the system. In addition, when the △Tsh decreased from 13 °C to 6 °C, the system efficiency increased significantly. When the △Tsh was below 6 °C, the growth rate of efficiency decreased gradually. And there was an optimal △Tsh that made the highest efficiency. The optimal △Tsh increased with the increase of engine speed at the same temperature conditions. When the engine speed were 1200 rpm, 1400 rpm, and 1600 rpm, the optimal △Tsh of the system were 3.5 °C, 3.8 °C and 4.5 °C, respectively. And the corresponding primary energy ratio of system were 2.63, 2.40 and 2.17, respectively.

Natural gas engine driven heat pump system – a case study of an office building

ABSTRACT An eQUEST model was developed to conduct a simulation study of a natural gas engine-driven heat pump (GEHP) for an office building in Woodstock, Ontario, Canada. Prior to the installation of the GEHP, the heating and cooling demands of the office building were provided by rooftop units (RTUs), comprising of natural gas heater and electric air conditioner. Energy consumption for both GEHP and RTUs were monitored for operation in alternating months. These recorded energy consumptions along with weather data were used in the regression analysis. The developed eQUEST models were validated and calibrated with the regression analysis results with respect to the ASHRAE Guideline 14–2014. The eventual models were then applied to investigate the potential annual energy consumption, greenhouse gas (GHG) emission and energy cost savings achieved by using the GEHP in Woodstock, and other cities in Canada, particularly in Ontario.

Experimental analysis of a novel gas-engine-driven heat pump (GEHP) system for combined cooling and hot-water supply

Abstract Heat pump technologies have been widely used in air conditioning and hot water application. However, most of the heat pump systems adopt an expansion valve to complete the cooling and heating modes currently. The flaw is that as the four-way valve is switched, the expansion valve cannot be guaranteed to be very close to the inlet of the evaporator in both modes, making the performance of the cooling or heating mode worse. In addition, for gas-engine-driven heat pump (GEHP), the utilization of engine waste heat is insufficient. Based on the above two shortcomings, a novel GEHP unit with an advanced finned tube heat exchanger and three thermostatic expansion valves was built in this work. The performance was evaluated under an experimental operating range of engine speed from 1300 rpm to 2000 rpm, air temperature from 23.8°C to 27.7°C, and evaporator water inlet temperature from 13.2°C to 22.4°C. Experimental results showed that when the engine speed and ambient temperature increased, the compression ratio increased, whereas the coefficient of performance (COP), primary energy ratio with heat recovery (PER1), and primary energy ratio without heat recovery (PER2) of the system decreased linearly. As the evaporator water inlet temperature increased from 13.2°C to 22.4°C, the COP, PER1, and PER2 had an improvement of 23.6%, 20.8%, and 27.6%, respectively. The averages of COP, PER1 and PER2 were 3.67, 1.57 and 0.96, respectively. The results indicated that the novel GEHP unit was able to maintain expected high performance.

Experimental Study of a Gas Engine-driven Heat Pump System for Space Heating and Cooling

In this paper, the performance of a gas engine-driven heat pump (GEHP) was experimentally studied for space heating and cooling. An experimental test facility was developed for this purpose. The effect of key parameters on system performance was investigated under both cooling and heating modes. The results showed that as the engine speed increased from 1400 to 2000 rpm, the cooling and heating capacities increased by 23% and 28.5%, respectively while the GEHP system Primary Energy Ratio (PER) decreased by 13.5% and 11.7% in the cooling and heating modes, respectively. The system PER in the cooling mode was found lower than that in the heating mode. This indicated that heat recovery from the engine cylinder and exhaust gas was very important for improving the GEHP system performance. In the heating mode, the ambient temperature and condenser water flow rate had a large effect on the system heating capacity and PER, and insignificant effect on the gas energy input. In the cooling mode, the chilled water inlet temperature showed a large effect on both cooling capacity and gas energy input while the chilled water flow rate had a large effect on cooling capacity and insignificant effect on the gas energy input.