燃气机热泵供暖过程的计算与分析

对驱动燃气机热泵的发动机余热产生规律进行了实验研究，并对燃气机热泵建立了一个计算模型。通过计算，分析了发动机余热对燃气热泵供暖过程的影响，着重分析了部分负荷下燃气机热泵的供暖过程的特点。以上海地区的气候条件和能源价格为基础，对燃气机热泵供暖的能耗和运行费用进行了分析比较。     

余热复合式燃气机空调数值计算及性能研究

建立了燃气机热泵空调系统模型,包括燃气发动机、压缩机、换热器、空调系统和建筑负荷模型。通过对模型的求解及结果分析,得到了燃气机热泵空调的性能。结果显示夏季燃气机热泵系统的二次换热器能够替代常规电力空调的电再热器实现空调风再热。冬季二次换热器能够实现系统余热直接向室内供暖,室外温度不太低时可以充分利用发动机余热实现房间供暖。室外温度较低时,可以实现发动机余热和热泵系统联合供暖,节能效果明显。在夏季系统的最大一次能源利用率能达到1.6以上,冬季最高能达到1.8以上。系统具有良好的能源利用效率。     

基于多元回归模型的燃气热泵系统制热性能分析

基于实测数据构建燃气热泵系统中天然气发动机的多元回归模型和开式涡旋压缩机的计算模型,采用EES软件对燃气热泵系统进行性能计算,分析出口水温(t_out)、发动机转速(N_eng)、环境温度(t_amb)及余热回收量对系统制热性能系数COP与一次能源利用率PER的影响。模拟研究表明：在同等条件下,不开启余热回收系统时,COP与PER随t_out增加线性降低,模拟值与实测值的最大误差分别为1.62%与3.06%;同时,t_amb对COP的影响较大,当N_eng为1 500 r/min时,随着t_amb从-15℃变化到24℃时,COP上升了225.87%,PER上升了217.26%;开启余热回收系统后,同等条件下的COP与PER分别提升了24.65%和24.67%,且COP,PER变化的趋势发生了明显变化。     

燃气机热泵部分负荷特性的实验研究

对燃气机热泵机组进行了部分负荷特性实验研究,重点分析了末端水流量和转速对其制热性能的影响规律.结果表明:冷凝器负荷、总余热、性能系数和一次能源利用率均随末端水流量的增大而增大,当末端水流量由1.8 m3/h增大到3.6 m3/h时,性能系数和一次能源利用率分别增大11.6％和19.5％;冷凝器负荷和总余热随发动机转速的...     

燃气机热泵的热力学分析

燃气机热泵是以燃气机作为动力来驱动的压缩式热泵。对燃气机热泵的热力学第一定律、Yong分析和能级平衡理论分析结果表明：其一次能源利用率可达1.76，Yong效率为0.291，能级平衡系数为0.394。与电动热泵等其他供热装置相比，燃气机热泵有着较高的热力学完善性，是一项高效节能技术。由于能级平衡理论分析考虑了Wu的作用，而热泵供暖时其性能系数的提高主要是利用了环境热量，所以建议采用能级平衡理论来分析评价热泵的性能。     

FBM车用醇基燃料的发动机性能试验研究

针对汽油短缺和燃用汽油产生大量污染等问题，研究了以工业甲醇、C5 、C1～C5，助溶剂和腐蚀抑制剂组成的FBM(fuel based on methanol)车用醇基燃料。对90^# FBM车用醇基燃料进行了发动机台架性能试验：起动性能试验，怠速排放性能测试，速度特性试验和负荷特性试验。试验结果显示：与燃用90^#汽油相比，发动机平均起动时间提前0．31S，表明了醇基燃料的冷机起动性能优于90^#汽油；排污低于90^#汽油；在100％油门开度下，转速在1000r／min至2800r／min之间，其最大功率比90^#汽油下降2．479，6，最大扭矩下降2．34％，最低燃料消耗率上升5．79％；1800r／min负荷特性试验结果，平均燃料消耗率比90^#汽油上升5．57％。     

辛烷值对均质压燃发动机燃烧特性和性能的影响

通过不同比例的正庚烷和异辛烷混合得到不同辛烷值的混合燃料，在一台单缸直喷式柴油机上研究燃料辛烷值对均质压燃发动机燃烧特性、性能和排放特性的影响．研究结果表明，燃料辛烷值增加，着火始点推迟，燃烧反应速率降低，缸内爆发压力降低．燃料辛烷值增高，均质压燃向大负荷工况拓宽，燃料辛烷值较高时，存在极限转速，辛烷值增加，极限转速降低．对于每一工况，存在一个最佳经济性的燃料辛烷值，负荷增大，最佳辛烷值增高；随着燃料辛烷值增高，发动机NO、HC和CO排放增加，尤其是HC排放增加更为明显．对于均质压燃发动机，低负荷工况适合燃用低辛烷值燃料，高负荷工况适合燃用高辛烷值燃料。     

压缩天然气发动机的设计及性能研究

为提升压缩天然气(CNG)发动机的综合性能,从考察、研究压缩天然气理化特性的角度出发,选择在一款柴油机原型机上改装天然气发动机,为天然气发动机设计燃料供给系统、进气系统、点火系统、燃烧系统以及后处理系统,以满足压缩天然气在发动机上的相关燃用要求。对改装设计的压缩天然气发动机开展台架试验研究,分析压缩天然气发动机的负荷特性、速度特性以及万有特性,并综合评价改装后的压缩天然气发动机性能表现。研究结果表明:相比于柴油机原机,改装设计的压缩天然气发动机最大转矩提高约22%,动力性增强;同时最小等热值有效燃油消耗率下降约2%,经济性获得改善;且压缩天然气发动机的升功率和比功率提升,发动机强化程度提高。     

氢-汽油双燃料发动机性能试验研究

介绍一种氢—汽油双燃料发动机，这种双燃料发动机装有余热制氢装置，可用甲醇制取氢并燃用氢与汽油混合燃料。作者对余热制氢装置及氢—汽油双燃料发动机的各项性能进行试验研究。试验结果表明，装有余热制氢装置的氢—汽油双燃料发动机功率和扭矩有所提高，外特性和负荷特性燃油消耗率下降5．3％一7．5％；怠速排放中CO和HC均有所减少。     

室外翅片管换热器的设计对空气源燃气机热泵系统性能的影响

研究了翅片管换热器的流路布置和支路数对空气源燃气机热泵系统性能的影响,研究结果表明:采用逆交叉流的流程布置方式空气源燃气机热泵的性能最好,而采用顺流的流程布置方式最差,与顺流相比,采用逆交叉流的流程布置方式空气源燃气机热泵性能提高了10%左右.翅片管换热器支路数采用14路比采用7路时空气源燃气机热泵性能提高了7%左右.因此,翅片管换热器的设计对空气源燃气机热泵系统性能有较大的影响,合理设计翅片管换热器对提高空气源燃气机热泵的性能起到了一定的作用.     

Theoretical Investigation of Waste Heat Recovery from an IC Engine Using Vapor Absorption Refrigeration System and Thermoelectric Converter

This study proposes the preliminary simulation of a single cylinder spark ignition engine with waste heat recovery system. To harvest waste heat energy from the engine exhaust a thermoelectric generator coupled to a vapor absorption refrigeration (VAR) system was proposed in this simulation work. Parametric simulation of engine, thermoelectric generator and VAR using thermodynamic relations was carried out in MATLAB – Simulink software. An attempt has been made mathematically to integrate engine, thermoelectric generator and VAR system to study the effect of engine load, speed, equivalence ratio on thermoelectric output and coefficient of performance (COP) of a VAR system. In this study, the VAR system runs by taking heat energy from the exhaust gas and the electric power produced by a thermoelectric generator was utilized to run the pump of the refrigeration system. It was found that COP of the absorption refrigeration system depends on engine load, speed and air fuel equivalence ratio. The study also reveals that about 10% to 15% of the total exhaust energy can be harvested using this system.     

Analysis on the heating performance of a gas engine driven air to water heat pump based on a steady-state model

In this study, the heating performance of a gas engine driven air to water heat pump was analyzed using a steady state model. The thermodynamic model of a natural gas engine is identified by the experimental data and the compressor model is created by several empirical equations. The heat exchanger models are developed by the theory of heat balance. The system model is validated by comparing the experimental and simulation data, which shows good agreement. To understand the heating characteristic in detail, the performance of the system is analyzed in a wide range of operating conditions, and especially the effect of engine waste heat on the heating performance is discussed. The results show that engine waste heat can provide about 1/3 of the total heating capacity in this gas engine driven air to water heat pump. The performance of the engine, heat pump and integral system are analyzed under variations of engine speed and ambient temperature. It shows that engine speed has remarkable effects on both the engine and heat pump, but ambient temperature has little influence on the engine’s performance. The system and component performances in variable speed operating conditions is also discussed at the end of the paper.     

Experimental study of gas engine driven air to water heat pump in cooling mode

Nowadays a sustainable development for more efficient use of energy and protection of the environment is of increasing importance. Gas engine heat pumps represent one of the most practicable solutions which offer high energy efficiency and environmentally friendly for heating and cooling applications. In this paper, the performance characteristics of gas engine driven heat pump used in water cooling were investigated experimentally without engine heat recovery. The effects of several important factors (evaporator water inlet temperature, evaporator water volume flow rate, ambient air temperature, and engine speed) on the performance of gas engine driven heat pump were studied in a wide range of operating conditions. The results showed that primary energy ratio of the system increased by 22.5% as evaporator water inlet temperature increased from 13 °C to 24 °C. On the other hand, varying of engine speed from 1300 rpm to 1750 rpm led to decrease in system primary energy ratio by 13%. Maximum primary energy ratio has been estimated with a value of two over a wide range of operating conditions.     

Heat pump enhanced gas turbine cogeneration

A significant fraction of the gaseous fuel supplied to industry will be used in medium- and small-size cogeneration plants. In this paper, a gas turbine and a gas engine of about 800 kW power output are compared at full and part load operation. When low-temperature heat (e.g., for space heating) is produced, the higher exhaust losses of the gas turbine yield a lower system efficiency, particularly at part load. A scheme is proposed to recover the exhaust gas energy by cooling to a temperature near ambient. The system features a heat pump to raise the recovered heat temperature to a usable level and an organic Rankine cycle (ORC) engine to drive the heat pump. The ORC engine uses the high-temperature fraction of the heat recovered from the exhaust. The data for the ORC engine are derived from an actual experimental engine. The performance is calculated for the system at full load.     

空气源单、双级燃气机热泵的应用及其效益分析

提出一种单、双级空气源燃气机热泵,并从多个角度上同传统的蒸汽压缩式热泵和单级燃气机热泵作了比较。结果表明,这种热泵在一次能源利用率、火用效率和经济性上有较大优势,它的推广使用将扩大热泵的适用范围和使用时间,尤其在三北地区。     

Modelling and validation of a gas engine heat pump working with R410A for cooling applications

Gas engine heat pumps play an important role in energy saving and environment protection in both cooling and heating applications. In the present work, a thermal modelling of the gas engine driven heat pump in cooling mode is performed and system main parameters such as cooling capacity, gas engine energy consumption and primary energy ratio (PER) are computed. The modelling of the gas engine heat pump includes modelling of the scroll compressor, the plate evaporator and the gas engine. Discharged refrigerant mass flow rate and compressor power represent the main output parameters of the compressor semi-empirical model. Using the discharged refrigerant mass flow rates along with the available evaporation heat transfer correlations, the system cooling capacity is deduced. Based on the present experimental data, a correlation of gas engine energy consumption as function of compressor power, engine speed and ambient air temperature is obtained. Furthermore, the gas engine heat pump model is validated by comparing experimental and simulation data. The model error percentages to predict the cooling capacity, the gas engine energy consumption and the PER are 7%, 5%, 6% respectively.     

热泵系统性能评价方法的探讨

基于热力学第一定律,反映热泵能量数量关系的性能指标-供热系数,在用于评价热泵系统节能效益及对热泵系统进行可行性评价的问题上,存在一定的局限性。本文对这一问题进行了分析。在此基础上,根据热力学第二定律,提出了以热泵系统单位火用损供热率作为其性能评价指标的思想。以此作为热泵系统的性能评价指标,更科学、更客观。     

基于相变储能的太阳能空气源热泵系统的研究

针对由天气变化导致太阳能利用不稳定和寒冷地区热泵性能低的问题,文章介绍了一种基于相变储能的太阳能空气源热泵系统,该系统能够根据气象情况灵活切换4种供暖模式,大大减少了系统耗电量。文章通过独特设计的储能冷凝器,不仅可以调节太阳能空气源热泵系统能量分配,改善太阳能空气源热泵系统制热量和建筑热负荷之间不平衡的供需关系、提高太阳能利用率,还可以提高空气源热泵低温性能,快速恢复供暖,从而实现提高太阳能空气源热泵系统整体性能的目的。文章以石家庄农村某户为研究对象进行研究,研究结果表明,太阳能空气源热泵系统供暖效果较好,太阳能空气源热泵系统COP最大值为5.19,节能环保效益十分明显。     

Cooling performance of a vertical ground-coupled heat pump system installed in a school building

This paper presents the cooling performance of a water-to-refrigerant type ground heat source heat pump system (GSHP) installed in a school building in Korea. The evaluation of the cooling performance has been conducted under the actual operation of GSHP system in the summer of year 2007. Ten heat pump units with the capacity of 10 HP each were installed in the building. Also, a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth was constructed for the GSHP system. To analyze the cooling performance of the GSHP system, we monitored various operating conditions, including the outdoor temperature, the ground temperature, and the water temperature of inlet and outlet of the ground heat exchanger. Simultaneously, the cooling capacity and the input power were evaluated to determine the cooling performance of the GSHP system. The average cooling coefficient of performance (COP) and overall COP of the GSHP system were found to be ～8.3 and ～5.9 at 65% partial load condition, respectively. While the air source heat pump (ASHP) system, which has the same capacity with the GSHP system, was found to have the average COP of ～3.9 and overall COP of ～3.4, implying that the GSHP system is more efficient than the ASHP system due to its lower temperature of condenser.