Criteria for use of groundwater as renewable energy source in geothermal heat pump systems for building heating/cooling purposes

Environmental protection measures are conducted directly by the use of renewable energy sources. The energy development of cities in Europe is aimed at the sustainable use of renewable energy sources in order to achieve the substitution of fossil fuels and the reduction of the hazardous gas emission into the atmosphere. Geothermal resources of medium and low enthalpy in Europe being used for obtaining heat energy are providing about 6600 MW_t, currently having the growth trend of 50 MW_t annually. The use of geothermal low enthalpy, namely of subgeothermal groundwater resources, has even higher annual growth rate, and if such a trend is kept till the year 2010, the produced energy will amount about 8000 MW_t. Criteria of the groundwater use as a hydrogeothermal energy resource in heat pumps are complex, and they deal with aspects of incoming temperatures and groundwater quantities. The precise limit temperature of groundwater that would separate the direct use of geothermal energy (only by the use of heat exchangers), and indirectly by the use of a heat pump has not been determined in the professional and scientific practice of Serbia so far. Taking into account that relatively small number of new flat is being built in Serbia nowadays, if we want to save energy it is necessary to carry out the energy reconstruction of the existing flats whose number is estimated to be more than 2.8 million. By the application of subgeothermal energy and the use of heat pumps, energy consumption would be significantly reduced.     

天然气-热泵组合在供暖空调中的应用

总结了几种天然气热泵组合运行方式,分析了各种方式的优缺点,并推导了相应的效能计算公式。比较了各种方式的运行费用,认为天然气热泵组合方式在供暖空调中很有发展潜力。     

燃气发动机驱动热泵一次能源利用系数的计算和分析

提出描述缸内工质复杂工作过程的零维物理模型和数学模型，用P－K法求得燃气机的性能参数。利用导出的燃气发动机驱动热泵装置一次能源利用系数PER的计算公式，分析并指出了供热系数、废热利用率和有效效率对PER的影响以及增大PER的有效途径。     

Development and experimental validation of a high-temperature heat pump for heat recovery and building heating

The performance of a high-temperature heat pump unit using geothermal water for heat recovery in buildings is experimentally evaluated. The unit consists of a twin-screw refrigeration compressor, a condenser, an evaporator and an oil cooling system. The effect of the cooled oil temperature on the performance of the heat pump unit is experimentally investigated. Results show that the unit stably produces outlet hot water at a constant temperature of 85 °C and performs well in a wide range of high-temperature conditions with a high energy efficiency ratio. The results also indicate that the key to improving the performance of a high-temperature heat pump unit often depend on the selection of proper cooled oil temperature. The optimum cooled oil temperature is 50-65 °C when the condensing temperature is above 70 °C. At these temperatures, the oil cooling system can increase the energy efficiency ratio of the heat pump by 6.3%.     

空气源热泵直接地板辐射供暖运行模式实验研究

对采用数码涡旋空气源热泵的直接地板辐射供暖系统的供暖性能进行了实验研究。分别测量了在连续和间歇运行模式下的室内温度、围护结构表面温度、地板表面温度和电能消耗量。引入操作温度的概念对两种运行模式下的热舒适性和能耗情况进行了分析比较。实验结果表明,连续供暖运行模式是一种理想的供暖运行模式,但其电能消耗量较大;对于一些特定住宅采用间歇供暖运行模式不仅能够较好地满足热舒适性要求,而且具有显著的节能效果。     

热泵型天然气热电冷联供系统实践研究

介绍了一类新型的热泵型天然气热电冷联供系统,系统利用吸收式制冷机在冬季兼作热泵运行,提高了系统的能源利用效率,降低了运行成本,除了增加一个回收冷凝热的换热器外,不会过多增加系统的额外初投资.通过对该系统的理论和实践研究表明,这类系统能充分利用天然气这种高品质能源,提高系统的综合利用效率.     

小区集中供热系统循环水泵电耗实测分析

对6个小区集中供热系统的17台循环水泵的电耗、实际运行效率、循环流量进行了实测,分析了造成小区集中供热系统输配能耗较高的原因,结合实例计算了各种能耗损失的大小和所占比例,给出了小区集中供热系统实际需求耗电量指标.     

Modeling and economic analysis of gas engine heat pumps for residential and commercial buildings in various climate regions of Iran

There is an increasing trend in using heat pumps in air conditioning (heating/cooling) systems of residential and commercial buildings. The required power to drive the compressor of vapor compression heat pump cycles may be provided by either an electrical motor or an internal combustion engine. In this paper thermal modeling and economic analysis of gas engine heat pumps (GEHPs) are presented based on energy and mass balance equations as well as the gas engine operating parameters (such as thermal efficiency, fuel consumption and fuel mass flow rate) and heat pump operating parameters (such as evaporator and condenser capacity and compressor input power). Based on the modeling results and with estimating GEHP fuel consumption, the economic analysis of using gas engine heat pumps (in comparison with the electrical heat pumps) at various climate regions of Iran, for both residential and commercial (office) buildings, and for both cooling and heating modes, was performed. Appropriate cost functions for predicting GEHP capital investment were proposed. Three approaches including equivalent uniform annual cost (EUAC), the annual cost of energy consumption, and payback period were applied in the economic analysis.     

关于分布式热水供暖系统选泵和调控问题的探讨

根据质量平衡和能量平衡的原理,分别探讨了设计工况、等流量比工况、非等流量比工况下单热源分布式热水供暖系统的选泵和调控,提出了按泵阻抗选泵的方法,绘制了选泵线算图,给出了相应的调控式。     

燃气锅炉烟气余热回收热泵系统应用与分析

对某烟气余热回收热泵系统进行了实测,结果表明,热泵综合能效比达到4.0以上。针对热泵系统应用过程中遇到的问题提出了改进措施,并从节能、经济和环境效益多角度对热泵系统进行了分析。     

Integration of variable refrigerant flow and heat pump desiccant systems for the heating season

Integration of the variable refrigerant flow (VRF) and heat pump desiccant (HPD) systems was investigated in a field performance test for a heating season. The HPD systems use only the moisture in the outdoor air and return air to humidify the indoors during ventilation in the heating season. Three different operating modes: non-ventilated, HPD ventilation assisted and HPD ventilation-humidification assisted VRF systems were investigated. It was found that the VRF systems provided an average of 93.5% of the total heating energy for the HPD ventilation assisted mode. The remainder was the recovered heat by the HPD systems during ventilation. The VRF systems provided an average of 46.8% of the total heating energy for the HPD ventilation-humidification assisted mode. The remainder was covered by the HPD systems which provided additional sensible and latent heating. Overall, among the three operating modes, it is concluded that the HPD ventilation-humidification assisted VRF outdoor units consume less energy than the HPD ventilation assisted ones (about the same energy as the non-ventilated ones), while providing the best indoor thermal comfort and indoor quality conditions. For the total system, the HPD ventilation-humidification assisted VRF systems consume less energy than the HPD ventilation assisted ones.     

烟气余热回收利用型溴化锂吸收式冷热水机的研发

介绍了烟气余热回收利用型溴化锂吸收式冷热水机在冷热电三联供系统中的应用。烟气高压发生器的设计采用数值仿真的方法,重点介绍了参数的选定、液管的布置以及压力损失和换热量的计算,并对数值仿真的计算结果进行了分析。     

Study on the performance of a solar assisted air source heat pump system for building heating

This paper proposed a new solar assisted air source heat pump system with flexible operational modes to improve the performance of the heating system. A mathematical model was established on the solar assisted air source heat pump system for building heating with a heating capacity of 10 kW, and an air source heat pump unit was developed to validate the model. The effect of the solar collector area on the performance of the system running in Nanjing was studied. The results showed that the COP of the heat pump unit was enhanced with the increase of the solar radiation density during the typical sunny day in the heating season. In addition, the COP also increased in proportion to the solar collector area. Compared with the case when the solar collector area was 0 m², the COP increase of the heat pump and the energy-saving rate were 11.22% and 24% respectively when the solar collector area was 40 m². Meanwhile, the solar equivalent generation power efficiency could reach 11.8%.     

天然气供热供冷的技术经济分析

对冬季采用天然气热水锅炉供热，夏季采用电动离心式冷水机组供冷和冬夏季都采用天然气直燃型溴化锂吸收式冷热水机组进行供热供冷的两种方案进行了技术经济比较。指出天然气价和电价是影响供热供冷成本的最敏感因素。     

单式磊空调水系统中旁通阀及水泵的选择

负荷减小时，单式果空调水系统可通过压差旁通调节阀控制流经末端设备的水流量。水泵、压差控制二通阀及旁通管管径的选择正确与否，会影响系统的调节性能及能耗。文中分析了空调系统部分负荷与水泵的能耗关系，给出了选择旁通调节阀、旁通管管径及水泵的方法。     

A unified model for the simulation of oil,gas and biomass space heating boilers for energy estimating purposes. Part II: Parameterization and comparison with measurements

A semi-physical model for the simulation of oil, gas and biomass space heating boilers has been parameterized based on measurements on nine different boiler units and simulation results have been compared to results obtained from measurements in steady state and transient operation. Although the agreement between simulated and measured boiler efficiencies was within the range of measurement uncertainties in most cases, model improvements are expected to be possible concerning the heat capacitance modelling in cycling on/off operation as well as influences of start and stop behaviour on the overall efficiency. It is found that electricity consumption during cycling on/off operation of small pellets or oil space heating boilers may have a significant influence on the overall energy balance of these units. This influence increases strongly with decreasing heat load and increasing number of on/off cycles.