A comparative study of solar assisted heat pump systems for canadian locations

The feasibility of solar assisted heat pump systems for space heating and domestic hot water preheating in Canada is examined by simulating the performance of these systems on a computer using the program WATSUN. Simulations are carried out using meteorological data for seven representative Canadian cities, two different building types, and six types of system configurations. For the solar assisted heat pump system, twenty year life cycle cost comparisons are made with two reference systems, namely a conventional resistance heating system and an air-to-air heat pump system, based on current economic parameters and projected escalation scenarios for electricity rates.Results of the study show that the solar assisted heat pump systems conserve significant amounts of energy over resistance heating and heat pump systems. On the life cycle unit cost basis, solar assisted heat pump systems costs are relatively insensitive to location, but the dependence on building types is substantial with multiplex dwellings showing the least cost. Liquid based dual source solar assisted heat pump systems are found to be cost effective over resistance heating (but not over an air-to-air heat pump system) at some of the locations for multiplex units. They are not cost effective for single family dwellings at the present time.     

Analysis of utilisation of renewable energies as heat sources for heat pumps in building sector in Poland

In this paper the emphasis is put on identification the problem how different renewable sources can be effectively used as heat sources for heat pumps in Poland. Main data of: ambient air, solar radiation, soil, ground and surface water are presented. Recommendations for heating systems with a heat pump are given.     

Energy consumption of a residential building: comparison of conventional and RES-based systems

The energy needs of a typical one-family house in the Thessaloniki area for heating, cooling and domestic hot water production are calculated. The calculations are based on the typical average daily consumption of hot water and on the degree-day method for heating and cooling. The results are finally translated into thermal energy consumption, assuming the typical Greek situation (heating with diesel oil boilers and conventional radiators, cooling with local air-to-air split-type heat pumps and hot water production with electric heaters). The same energy needs are assumed to be covered by a vertical closed loop ground heat exchanger combined with a water-to-water heat pump system with fan-coils for heating and cooling and a thermosyphonic solar system for domestic hot water production. The ground heat exchanger/heat pump system efficiency is determined using data from an existing and continuously monitored similar system installed in the broader area of Thessaloniki. The solar system load coverage is calculated using the f-chart method. The energy consumption of the renewable energy systems is calculated and compared to that of the conventional system. The results prove that significant energy savings can be achieved.     

Electrical and engine driven heat pumps for effective utilisation of renewable energy resources

Much of the energy used for domestic, commercial and industrial purposes is to provide efficient and effective heating of conditioned spaces and for specialist niche applications in process heat systems. Vapour compression heat pumps driven by electric motors or engines provide the real capability of upgrading low temperature sources of ambient and waste heat to match the desired load temperatures in such heating applications. Major source of ambient heat stem from the storage of solar energy in the ground, in lakes and rivers, and in atmospheric air. Heat pumps can therefore be used to effectively harness indirectly the daily solar radiation input. In addition many industries have major sources of waste low grade heat in the form of air or water discharged from the industrial process heat stream. Heat pumps are generally formally classified therefore as air source, ground source or water source units although there has also been considerable interest recently in hybrid units combining the attributes of two or more of these specific types mentioned above.     

Performance of combined solar-heat pump systems

A comparative study of the performance of combined solar heat pump systems for residential space and domestic hot water heating has been undertaken. Simulations have been made with TRNSYS[1] of three basic combined configurations, as well as conventional solar and conventional heat pump systems, in two different climates, Madison, Wisconsin, and Albuquerque, New Mexico.The three combined systems are the series system in which the solar storage is used as the source for the heat pump, the parallel system in which ambient air is used as the source for the heat pump, and the dual source system in which the storage or ambient is used as the source depending on which source yields the lowest work input. The influence of collector area, number of glazings, main storage volume to collector area ratio, and heat pump coefficient of performance were determined.The results indicate that the parallel combined system is probably the most practical solar-heat pump configuration. The thermal performance at a given collector area is consistently superior to both the series or the dual source systems over the heating season. Costs and the extent to which summer cooling is a requirement determine the relative merit of the conventional heat pump, conventional heat pump, conventional solar, and parallel systems.     

建筑节能新方向:太阳能光伏-地源热泵系统

减少我国冬季采暖所造成的大气污染,降低供暖系统的能耗,节约能源一直是建筑节能追求的目标.目前太阳能光伏发电已经成为人类利用太阳能的最主要方式之一,地源热泵已被作为一项旨在解决建筑冷热源问题的新技术,日渐受到人们的重视.将光伏转换与热泵循环有机结合在一起,从而形成了太阳能光伏-地源热泵系统.该系统提高了光电转换和光热吸收效率,光电/光热综合利用,极大地提高了单位面积太阳辐照的利用效率,同时可提高热泵系统在寒冷地区运行的适用性;利用光电效应把太阳能中高能带区域的光能直接转化成电能,可大大提高太阳能的可用能效率;在增加能量储存装置和逆变器的条件下,可以使系统脱离公用电网运行,从而增加了系统的适用性和灵活性;与普通的空气源热泵相比,太阳能地源热泵具有较高的热性能,具有一机多用的功效;与建筑物相结合的太阳能热泵系统,可以增加建筑物的隔热效果,起到减少建筑物冷暖负荷的作用,同时可极大地减少环境污染.     

A review of heat pump systems for heating and cooling of buildings in China in the last decade

Heat pump technology fully shows the principle of energy recycling in terms of Heating, Ventilating and Air Conditioning (HVAC). It avoids unipolarity of energy using in the conventional HVAC system. Heat pumps use high-grade energy as a driving energy, recovering and upgrading low-grade energy for avail, like a pump. Because heat source used in HVAC usually is low temperature heat, heat pump systems adopted in HVAC will help improve heating performance coefficient. Therefore, HVAC is one of ideal users of heat pump applications, and thus high-grade energy used in HVAC can be replaced with a large number of low-temperature renewable energy. Through the heat pump technology, natural low-grade energy stored in the soil, water, air or waste heat from variant industries and daily lives, is supplied for building cooling/heating and hot water serving. Therefore, vast applications and developments of heat pump technology are presented in HVAC in China, and some progresses are achieved in the system innovation, experimental research, product development and engineering application, etc. This paper reviews the progress of researches, applications and development in the field of heat pumps for building cooling/heating in China since the 21st century.     

Energy and exergy analysis of fossil plant and heat pump building heating system at two different dead-state temperatures

In this paper, we deal with the energy and exergy analysis of a fossil plant and ground and air source heat pump building heating system at two different dead-state temperatures. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for heat pump building heating system. Since energy and exergy demand are key parameters to see which system is efficient at what reference temperature, we did a study on the influence of energy and exergy efficiencies. In this regard, a commercial software package IDA-ICE program is used for calculation of fossil plant heating system, however, there is no inbuilt simulation model for heat pumps in IDA-ICE, different COP (coefficient of performance) curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy. The outcome of the energy and exergy flow analysis at two different dead-state temperatures revealed that the ground source heat pumps with ambient reference have better performance against all ground reference systems as well as fossil plant (conventional system) and air source heat pumps with ambient reference.     

太阳能吸收式空调系统的经济性分析

针对一个特定的对象,进行了太阳能吸收式空调系统寿命周期内的模拟计算及影响因素的分析,结果表明：（1）单纯太阳能空调（无采暖与热水供应）的经济性很差,太阳能空调与供热的复合系统的经济性要优于单纯的太阳能空调系统;（2）太阳能采暖与空调的复合系统,采暖与供冷的负荷比对系统的经济性有很大影响,即使在最佳的负荷比时仍无法和常规的系统竞争;（3）太阳能与生活热水系统的负荷系统中,热水负荷所占比重越大,经济性越好,当太阳能空调使用生活热水系统夏季多余的热量时,太阳能空调系统经济上可以和天然气锅炉＋电动制冷机竞争,并具有很好的节能性和环境效益。     

Net energy analyses of four technologies to provide residential space heat

After having calculated energy ratios for four methods of providing residential space heat, passive solar heating systems were found to return approx. 20–25 units of energy for each unit of energy invested. The other technologies (active solar, electrically powered heat pump, and a synthetic gas fueled hot air furnace) had energy ratios of 1.7–5.6. The low energy ratios for active solar energy systems (both air and water) and conventional space heating methods are due to the fact that these technologies employ energy-intensive materials in the equipment used to produce and distribute residential heat. Passive solar energy systems use few components beyond the relatively low energy intensity materials used for standard construction techniques and generally use no energy to distribute the captured heat. Based on these estimates and projected life cycle costs for these energy producing techniques, as well as on some standard energy-conserving techniques, it is apparent that the United States would produce more energy per dollar and energy input with conservation and passive solar strategies than with residential heating techniques depending on coal as a primary fuel.     

以太阳能/空气为热源的直膨式热泵热水系统

介绍了一种直膨式太阳能热泵空调及热水系统。针对春季供热水工况，分别对以太阳能及空气为热源生产生活热水进行了比较，发现以太阳能为热源具有更高的COP值，节能效果更为显著；根据试验数据分析了压缩机工作频率、太阳辐射强度、环境温度等因素对热泵系统性能系数的影响。     

Solar space heating and cooling with bi-heat source heat pump and hot water supply system

This paper describes a specific heat pump system that can solve the problem of low heating capacity at a low ambient temperature—one of the largest problems in the air-source heat pump system.

In order to decrease the collector area required, the heat pump system is operated by the air-source during the daytime, but at night or at a very low ambient temperature it can be operated with hot water which has been produced by the collector in the daytime. The effect of the solar energy on the air-source heat pump system has many advantages in the moderate winter climate of Japan. The hot water supply system includes an auxiliary electric heater.

The experiment has been carried out with a prefabricated test house, which has been constructed in Nara with double glazed windows and high thermal insulation. The results of this experiment are that solar energy enhances the total electric energy savings, increases the heating capacity at low ambient temperature, and eliminates the need for reverse cycle defrosting operation, etc.     

广东地区太阳能-空气源热泵复合系统供暖供生活热水实验研究

构建了一种太阳能-空气源热泵复合供热系统,在广东地区冬季的晴天和全阴天进行供暖供生活热水实验测试。针对办公建筑供暖供生活热水需求,定时间段供生活热水同时进行供暖实验。实验结果表明:晴天热泵相较于全阴天工况节电1.16 kW·h,供热效果优于全阴天工况,太阳能-空气源热泵复合供热性能相较于单独的空气源热泵更有显著优势;太阳能-空气源热泵复合系统供暖供生活热水期间,复合系统COP_(sys)平均值为4.71、波动范围在4.20～5.38,空气源热泵系统COP_(hp)平均值为4.60、波动范围在4.08～5.10。     

The cost-effectiveness of heat pumps in specific buildings in South Africa

Water heating heat pumps are extremely energy efficient and large savings can be realized when they are compared to direct electrical resistance heaters. In spite of the energy efficiency of heat pumps, a large number of residential buildings in South Africa still use electrical heaters to heat water. The reason for this is that heat pumps are considerably more expensive than electrical heaters. Building owners tend to choose the system with the smallest initial cost and do not compare the two systems on the basis of life-cycle cost. It is also difficult to calculate the life-cycle cost of a heat pump because it depends on many factors like climatological conditions and water temperature. In this paper a methodology is developed to calculate the life-cycle cost of a heat pump hot water installation. The model is used to investigate the effect of daily runtime, electricity tariff, hot water consumption and geographical location on the cost-effectiveness of heat pumps. The cost-effectiveness of heat pumps increases with daily run time, water consumption and electricity tariff. Heat pumps are more cost-effective near the coast than in the interior. If sized correctly, heat pumps are more cost-effective than electrical heaters for all major cities in South Africa. The cost-effectiveness of heat pumps for two specific buildings, one a university student hostel in Potchefstroom and the other a hotel in Durban, is also investigated. For both cases it was found that heat pumps are more cost-effective than direct electrical resistance heaters.     

Modeling and application of direct-expansion solar-assisted heat pump for water heating in subtropical Hong Kong

Direct hot water production consumes about 4% of the total energy use in Hong Kong, and about 20% when considering only the domestic sector. For water heating the energy sources are mostly town gas, liquefied petroleum gas and electricity. The use of heat pump or solar water heating, particularly the solar-assisted heat pump options, is not popular. In this paper, the potential application of a unitary type direct-expansion solar-assisted heat pump (DX-SAHP) system was examined. A numerical model of the DX-SAHP system was first introduced. From the simulation results with the use of the Typical Meteorological Year (TMY) weather data of Hong Kong, the system was found achieving a year-average coefficient of performance (COP) of 6.46, which is much better than the conventional heat pump system performance. The potential use of DX-SAHP therefore deserves further evaluation.     

Parametric Analysis of Solar Heating and Cooling Systems for Residential Applications

Abstract

In this paper, a parametric analysis of two solar heating and cooling systems, one using an absorption heat pump and the other one using an adsorption heat pump, was performed. The systems under investigation were designed to satisfy the energy requirements of a residential building for space heating/cooling purposes and domestic hot water production. The system with the absorption heat pump was analyzed upon varying (i) the solar collectors’ area, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The system with the adsorption heat pump was evaluated upon varying (i) the inlet temperature of hot water supplied to the adsorption heat pump, (ii) the volume of the hot water storage, (iii) the volume of the cold water tank, and (iv) the climatic conditions. The analyses were performed using the dynamic simulation software TRNSYS in terms of primary energy consumption, global carbon dioxide equivalent emissions, and operating costs. The performance of the solar heating and cooling systems was compared with those associated with a conventional system from energy, environmental and economic points of views in order to evaluate the potential benefits.     

A review on the energy and exergy analysis of solar assisted heat pump systems

During the last decade, a number of studies have been conducted by various investigators in the design, modeling and testing of solar assisted heat pump systems (SAHPSs). This paper reviews the studies conducted on the energy and exergy analysis of SAHPS systems in Turkey and around the world as of the end of December 2004. The studies undertaken on the SAHPS systems are categorized into four groups as follows: (i) SAHPSs for water heating, (ii) SAHPSs with storage (conventional type) for space heating, (iii) SAHPSs with direct expansion for space heating, and (iv) Solar-assisted ground source heat pump greenhouse heating system (SAGSHPGHS). This paper investigates the studies on SAGSHPs, especially ground-source heat pumps, also known geothermal heat pumps, at the Turkish universities in more detail, by giving Turkey's solar energy potential.     

Economic comparison of solar-assisted heat pumps

A study of the economic performance of a solar system, air-to-air heat pumps, and several solar-assisted heat pump systems (SAHP) for residential heating is presented. The study is based on a computer simulation which is supported by monitoring data from an existing installation, the Terrosi-Grumman house in Quechee, Vermont. Three different SAHP configurations as well as conventional solar and air-to-air heat pump systems are evaluated for a northern New England climate. All systems are evaluated both with and without a peak/off-peak electricity price differential.

The SAHP systems are: (1) the series system in which the solar storage serves as the energy source for the heat pump, (2) the series off-peak system in which the heat pump in the series system operates only during certain periods of the day under a special electric rate structure, (3) a parallel system in which the environment is the source for both the collector and the heat pump, and (4) a peak/off-peak parallel system in which oil is operated during the period of peak electricity price. Hybrid air-to-air heat pump/oil systems are also evaluated.

For all alternatives, two different economic analyses are used: (1) the rate of return which emphasizes the return earned on the capital investment, and (2) the life cycle critical price which compares the current capital cost to the present worth of the stream of all future energy savings.

Both economic measures select the air-to-air heat pump/on-peak oil system when there is a peak/off-peak electricity price differential. (In this case the ratio of off-peak to average price is 40 per cent.) When there is no price differential, the air-to-air heat pump/oil system is still preferred, but the oil system is now operated when the ambient temperature falls below −6.7°C (20°F). When the electricity price is doubled (from 19.5 to 40$/GJ), solar/oil is the preferred system.     

别墅型建筑地源热泵空调系统设计

地源热泵是一种利用土壤所储藏的太阳能资源作为冷热源进行能量转换的供暖制冷空调系统,通过输入少量的高品位能源(如电力、机械功、燃气和液体燃料),实现热量从低温热源向高温热源的转移.以上海某小型别墅为对象,设计了一套家用地源热泵空调系统.首先计算了夏季冷负荷和冬季热负荷,然后根据冷、热负荷选择一套水源热泵机组(MWH080CR型机组)和相应的风机盘管,进行了室内水管环路系统、土壤热交换器和地板采暖的设计选型,最后对系统的能效比进行了计算.结果表明,该空调系统具有节能环保、稳定可靠、舒适耐用等优点.     

太阳能制冷与供暖系统的设计与比较

根据上海的气候条件，以上海地区某写字楼为对象，提出4种太阳能驱动的溴化锂吸收式与电动蒸汽压缩式热泵联合制冷与供暖系统。这4种系统分别由热管式真空管集热器或抛物面槽形聚光集热器，单效或双效溴化锂吸收式制冷机，以及风冷热泵或水源热泵构成。分析比较这4种系统的节能型和经济性的结果表明，采用抛物面槽形聚光集热器＋双效溴化锂吸收式制冷机＋风冷热泵组成的系统，同时具备较好的节能性与经济性，一次能源利用率可降低约50％。