地源热泵与风冷热泵的技术经济性能比较

通过对地源热泵系统与风冷热泵系统在技术性能和经济性能方面进行的对比，显示了地源热泵的特点，并通过对工程运行的实测，验证了地源热泵的突出效果。研究结果表明：地源热泵比风冷热泵等传统空调系统具有明显的优势，是今后发展潜力最大的空调技术之一。     

化霜控制方式对分体空调性能影响的研究

针对目前分体空调在极端寒冷季节制热时化霜过程出现冷凝器底部及外机底盘化霜不彻底、能耗较大的问题,首次从电热管的化霜控制方式入手,提出一种针对冷凝器底部化霜更为彻底的优化方法。实验结果表明:通过化霜控制方式的的改变,底盘化霜的效果得到很好的改观,整体运行能效有了较大的提高,提升了冬季制热效果。优化后方法具有很好的实用价值和推广意义。     

Performance analysis of a novel dual-nozzle ejector enhanced cycle for solar assisted air-source heat pump systems

In this study, a novel dual-nozzle ejector enhanced vapor-compression cycle (DEVC) for solar assisted air-source heat pump systems is proposed. In DEVC, the use of the dual-nozzle ejector for recovering the expansion losses is a very promising approach to improve the cycle performance. A mathematical model of the DEVC is developed to predict its performance under specified operating conditions. The simulation results indicate that for the range of given operating conditions, the coefficient of performance (COP) and the volumetric heating capacity of the novel cycle using refrigerant R410A are theoretically improved by 4.60–34.03% and 7.81–51.95% over conventional ejector enhanced vapor-compression cycle (CEVC), respectively. The results imply that the solar-air source heat pump systems could take advantage of the best features of the DEVC. The potential use of DEVC therefore deserves further experimental validation. It is expected that this new cycle will be beneficial to developing dual-source coupled heat pump applications.     

Comparison between hot-gas bypass defrosting and reverse-cycle defrosting methods on an air-to-water heat pump

Frost build-up blocks the gap between fins and decreases the airflow rate, and the heating capacity and COP of air-source heat pump become lower. The reverse-cycle defrosting (RCD) and hot-gas bypass defrosting HGBD are the two common methods of frost removal. The comparison between the RCD and HGBD methods on one heat pump were not found by authors up to now. This paper compared the dynamic characteristics during the RCD and HGBD periods on one medium air-to-water heat pump of 55 kW. The feasibility of the HGBD method without heat provided to evaporate the liquid refrigerant after melting frost, which was supposed in the danger of the compressor liquid slugging, was especially discussed. The results showed the liquid refrigerant leaving the air cooled coils for the HGBD method was trapped in the suction accumulator and flashed into the saturated gas by the compressor pumping action, and no compressor liquid slugging happened in our tests. The HGBD time was much longer than the RCD time. The amenity for the HGBD method was better than that for the RCD method, due to lower refrigerant noise, smaller indoor temperature fluctuation, and no cold blowing. The suction superheat and discharge superheat for the HGBD method were lower than those for the RCD method. The HGBD could overcome the main disadvantages of the RCD method and deserved the further investigation.     

空气源热泵烤烟房温度波动特性实验研究

针对空气能热泵烤烟房有效烘烤加热时间短,烘烤温度波动大等问题,进行空气能热泵烤烟房温度波动特性实验研究,分析影响空气能热泵烤烟房温度波动的有关因素。实验表明：有PLC通电自检比无PLC通电自检的温度波动最低值低1.7℃;热泵开机延时30s比热泵开机延时15s的温度波动最低值低0.9℃;无电辅热比有12kW电辅热的温度波动最低值低0.4℃;热泵烤烟房存在15～30s的热泵过渡时间,热泵过渡时间越小,热泵烤烟房温度波动越小;在无PLC通电自检,热泵开机延时0s,有12kW电辅热工况下,热泵烤烟房有效烘烤加热效率在58℃取得极小值;烤烟控制器控温范围只影响热泵烤烟房温度波动的振幅。     

空气源热泵空调系统节能分析

节能的分析及优化已不仅仅是能的量的问题，而是能的质与量的综合评价的问题。采用yong分析方法得出空气源热泵空调系统的能耗分布，明确系统yong损失较大的环节。从yong分析得知：压缩机的yong损失占机组能耗的20．5％，冷凝器的yong损失接近总能耗的30％。由此提出了空气源热泵空调系统的节能措施，即应该选用高效率的压缩机，采用强化传热措施，提高传热系数，减小传热温差，同时还应注意改善热泵机组的周围环境，使系统yong损失最小，yong效率最大，实现空气源热泵空调系统的节能优化.     

空气源热泵系统在酒店的应用与发展

从空气源热泵系统的工作原理和特点着手,并结合工程实例,突出介绍其节能的优越性和广阔的应用前景。实例中空气源热泵系统于2009年竣工投入运行,经节能监测部门跟踪监测,经济效益和社会效益可观。     

地源热泵实验研究用地下换热系统

地下换热装置对于地源热泵系统的稳定运行和地源热泵系统的投资起着关键的作用。为了对地下换热系统换热效果和周围土壤的温度场进行试验研究,在北京工业大学高科技能源楼建立了一套包含60种不同结构的地下换热系统的实验台,探求不同结构地下换热系统的换热情况。试验系统不仅为地源热泵的设计提供了数据,而且为地源热泵的深入研究提供了平台。     

Experimental research and operation optimization of an air-source heat pump water heater

In order to optimize design and operation strategy of air-source heat pump water heater, an experimental set-up and simulation model were constructed. Also, a methodology of optimizing operation, which takes into account thermostatic and timing control patterns, was presented and applied. Experimental results indicated that the average COP ranged from 2.82 to 5.51 under typical conditions. The recommended outside area ratio of condenser coil to evaporator is 0.14−0.31 when the evaporator outside area is between 6.0 and 6.5 m² for this set-up. The optimal start-up time was between 12:00 and 14:00 if there was no electricity price difference between day and night, or it was near 22:00. The optimal setting water temperature should be adjusted according to the variation of seasonal ambient temperature. It was suggested that, based on this set-up, setting water temperature should be set higher than 46 °C in summer and 50 °C in other seasons.     

空气能热泵热水器的现状及展望

近年来空气能热泵热水器因其明显的安全性、节能性,受到了广大消费者的关注,显示出巨大的市场潜力。本文简要介绍国内空气能热泵热水器的发展背景、运行机理及研发现状,并与传统三大热水器作了比较分析,概括说明空气能热泵热水器国内的市场状况,指出该产品目前亟待解决的问题。     

Exergy analysis and experimental study of heat pump systems

Exergy analysis of heat pump—air conditioner systems has been carried out. The irreversibilities due to heat transfer and friction have been considered. The coefficient of performance based on the first law of thermodynamics as a function of various parameters, their optimum values, and the efficiency and coefficient of performance based on exergy analysis have been derived. Based on the exergy analysis, a simulation program has been developed to simulate and evaluate experimental systems. The simulation of a domestic heat pump—air conditioner of 959 W nominal power (Matsushita room air conditioner model CS-XG28M) is then carried out using experimental data. It is found that COP based on the first law varies from 7.40 to 3.85 and the exergy efficiency from 0.37 to 0.25 both a decreasing function of heating or cooling load. The exergy destructions in various components are determined for further study and improvement of its performance.     

多联机不停机除霜的蓄热模块设计及实验研究

多联机热泵空调除霜技术一直是行业内的研究热点。通过仿真模拟对比了螺旋结构和平铺矩阵结构的蓄热模块对制冷剂管路放热的情况,选用了综合性能更优的平铺矩阵结构的蓄热模块与一台10HP多联机热泵空调器进行除霜匹配初步试验,结果表明,该独立蓄热模块不需要消耗热泵本身循环的热量,除霜期间完全不影响室内换热器的供热需求,除霜时间短,两次除霜间隔时间内,蓄热模块能顺利蓄热,实现了真正不停机除霜。     

Concept study of a new method for drying dishware in a heat pump dishwasher

In a heat pump dishwasher, the whole dishwasher with the cabinet, dishware and process water is the heat sink, while a water tank, whose contents will freeze, is the heat source. The aim of the experimental concept study presented here was to evaluate a new drying method for a heat pump dishwasher. In this method, the drying of the dishware occurs as a fan circulates humid air in a closed system in which the water on the dishware evaporates inside the warm dishwasher cabinet and then condenses on a cold surface of the frozen water tank. The evaluation of drying performance was based on the European standard EN50242, which considers visible water drops left on the dishware after a completed dishwashing cycle. The results showed that this new closed drying method was more energy efficient compared to an existing open drying method and that the drying start temperature and the drying time had a significant effect on the drying performance. Its lower electricity consumption and the fact that it does not vent humid air into the kitchen give this heat pump dishwasher a competitive advantage over dishwashers using an open drying method.     

Theoretical and experimental studies on optimum heat rejection pressure for a CO2 heat pump system

The experimental and simulation researches have been conducted to investigate the relationships between optimum heat rejection pressure and other related operating parameters for a transcritical CO₂ heat pump system with two throttle valves. It proved that it is relatively reliable to control the heat rejection pressure of the CO₂ system with two expansion valves in series. The experimental results also show similar trends with those from simulation, under widely different operating conditions. Thus both the simulation and experimental results meet here: for a transcritical CO₂ cycle, there exists an optimal heat rejection pressure, under which the system can reach the maximum heating coefficient of performance (COP). Furthermore, the research also reveals that the optimal heat rejection pressure mainly depends on the refrigerant outlet temperature of gas cooler whereas the evaporating temperature and the performance of the given compressor have smaller effect on the optimum heat rejection pressure. Based on the experimental data, a correlation of the optimal heat rejection pressure with respect to mainly involved parameters is obtained for specific conditions.     

工质为R415b的空气源热泵热水器性能实验研究

通过对工质为R415b的空气源热泵热水器的性能实验,给出了环境温度和相对湿度不同时,随着水箱内水温的升高,热泵系统内蒸发压力、冷凝压力、压比、吸气温度、液管温度、冷凝侧过热度和过冷度、蒸发侧过热度以及COP的变化规律,指出了空气源热泵热水器的COP不仅随水温动态变化,而且与气温及湿度有关。同时,还对水箱内水的升温规律以及与热泵循环参数的关联进行了研究。     

Performance of a novel mechanical ventilation heat recovery heat pump system

The ventilation, heating and cooling of a building can be provided by advanced mechanical ventilation heat recovery systems (MVHR) which incorporate heat pumps. This paper covers the testing and performance of a novel MVHR heat pump system developed for the domestic market [S.B. Riffat, The University of Nottingham: Patent no. GB9522882.1, 1995; Patent no. GB9522882.1, 1996; Patent no. GB9507035.5, 1995]. The novel system uses revolving heat exchangers which both impel air and transfer heat. Low grade heat recovered from the exhaust air is upgraded by a heat pump and used for heating the fresh supply air. The system typically provides 2 kW of heating for air supplied at 250 m³/h. The prototype system has a heating coefficient of performance (COP) of up to 5 and an average system of COP 2.5 over a range of conditions. The system can also be used for cooling by switching the air flows over the evaporator and condenser. The prototype system requires very little maintenance and is compact and energy efficient.     

Dynamic defrosting characteristics of air source heat pump and effects of outdoor air parameters on defrost cycle performance

The reverse-cycle defrosting characteristics of a 11.2 kW split-type air source heat pump (ASHP) were experimentally investigated under the defrosting conditions. Based on the experimental results, the effects of outdoor air parameters on defrosting cycle performance as well as the dynamic defrosting characteristics of the ASHP unit were analyzed. The experimental results indicate that with the increase of the outdoor air relative humidity at a constant air temperature and velocity, the total power consumption, defrosting time and endotherm from indoor room during defrosting period decreased linearly, and they also decreased as the outdoor air temperature increased, but the trends of the curves presented the concave-up. The duration of the defrosting period mainly depends on the wall temperature of outdoor heat exchanger, which is corresponding to the condensing pressure during the defrosting cycle. In this paper, the concept of total coefficient of performance (COP) is used to evaluate the performance of ASHP unit, and as the air temperature increased under the conditions of a fixed air relative humidity and air velocity, the total COP increased linearly, but it decreased linearly as the air relative humidity increased.     

Year round experimental study on a constant temperature and humidity air-conditioning system driven by ground source heat pump

Numerous studies about the ground source heat pump building heating and cooling systems have been constructed in office building, hotel, residential building and school et al. However, few researches about the constant temperature and humidity air-conditioning system driven by ground-coupled heat pumps were carried out. In this paper, a constant temperature and humidity air-conditioning system driven by ground source heat pump was designed and constructed in an archives building in Shanghai, China. During the operation in the cooling mode, the heat extraction from the condenser of the heat pump was divided: part was rejected to the soil while another was used to reheat the air in AHUs. According to the experimental results, the indoor temperature and relative humidity fulfilled the “Archives Design Code”. In summer, the heat rejected to the soil was reduced by 32%, which was helpful for the earth energy conservation. The soil temperature increased only 0.5 °C after the GSHP system operating for a year. The energy cost of the air-conditioning system was 56.1 kWh/m². Compared with air source heat pump system and water cooled unit with boiler system, the operating cost of ground source heat pump was reduced by 55.8% and 48.4%, respectively.     

A novel design and experimental study of a cryogenic loop heat pipe with high heat transfer capability

A cryogenic loop heat pipe (CLHP) has been developed for future aerospace applications at TIPC (Technical Institute of Physics and Chemistry). This article presents a novel design of a cryogenic loop heat pipe and corresponding test system. The CLHP studied in this work has demonstrated to be able to operate in liquid-nitrogen temperature range using nitrogen as working fluid and to transfer large amount of heat over long distance with very small temperature difference. This device has been tested at three different orientations with respect to the relative position of the liquid line and the vapor line. The experimental results show that the CLHP can have a heat transfer capability of up to 12 W under horizontal and adverse gravity orientations and up to 20 W in liquid-nitrogen temperature range under gravity-assisted orientation.