游泳池太阳能加热系统的设计

ISO标准《游泳池太阳能加热系统的尺寸、设计和安装指南》,是一部关于游泳池太阳能加热系统的设计、安装及试运行的推荐标准,它包括了泳池加热负荷的计算和有关泳池罩的资料。现将其中     

Performance analysis and cost optimization of a solar-assisted heat pump system

A solar-assisted heat pump system with a conventional backup unit was simulated for a 93 m² (1000 ft²) house in Rhode Island using quasi-dynamic computer models. The performance of the system as a function of collector area and thermal storage volume was evaluated to determine the fraction of the space heating and domestic hot water load that was supplied by the solar-assisted system. This information was used to compute the payback time, based on cumulative costs, for each variation of the system's parameters when compared to a conventional system. The optimal combination of system components which had a payback time less than the mortgage life was determined. For the given initial costs of solar panels and storage reservoir, this optimal combination was found to be insensitive to the variations in mortgage and fuel cost growth rates presented in this report.     

Solar swimming pool heating: Description of a validated model

In the framework of a European Demonstration Programme, co-financed by CEC and national bodies, a model was elaborated and validated for open-air swimming pools having a minimal surface of 100 m² and a minimal depth of 0.5 m. The model consists of two parts, the energy balance of the pool and the solar plant. The theoretical background of the energy balance of an open-air swimming pool was found to be poor. Special monitoring campaigns were used to validate the dynamic model using mathematical parameter identification methods. The final model was simplified in order to shorten calculation time and to improve the user-friendliness by reducing the input values to the most important ones. The programme is commercially available. However, it requires the hourly meteorological data of a test reference year (TRY) as an input. The users are mainly designing engineers.     

System performance and economic analysis of solar-assisted cooling/heating system

The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling load to reduce the energy consumption of the air conditioner installed as the base-load cooler. A standard SACH-2 system for cooling load 3.5 kW (1 RT) and daily cooling time 10 h is used for case study. The cooling performance is assumed only in summer seasons from May to October. In winter season from November to April, only heat is supplied. Two installation locations (Taipei and Tainan) were examined.It was found from the cooling performance simulation that in order to save 50% energy of the air conditioner, the required solar collector area is 40 m² in Taipei and 31 m² in Tainan, for COP_j = 0.2. If the solar collector area is designed as 20 m², the solar ejector cooling system will supply about 17–26% cooling load in Taipei in summer season and about 21–27% cooling load in Tainan. Simulation for long-term performance including cooling in summer (May–October) and hot water supply in winter (November–April) was carried out to determine the monthly-average energy savings. The corresponding daily hot water supply (with 40 °C temperature rise of water) for 20 m² solar collector area is 616–858 L/day in Tainan and 304–533 L/day in Taipei.The economic analysis shows that the payback time of SACH-2 decreases with increasing cooling capacity. The payback time is 4.8 years in Tainan and 6.2 years in Taipei when the cooling capacity >10 RT. If the ECS is treated as an additional device used as a protective equipment to avoid overheating of solar collectors and to convert the excess solar heat in summer into cooling to reduce the energy consumption of air conditioner, the payback time is less than 3 years for cooling capacity larger than 3 RT.     

游泳池加热负荷的计算--译自ISO标准《游泳池太阳能加热系统的尺寸、设计和安装指南》

利用太阳能加热游泳池水是太阳能应用中的一个重要方面,设计者必须知道游泳池的需热量。即加热负荷。泳池加热负荷是游泳池的总热损失减去从入射辐射中获得的增热。总热损失是由于蒸发、辐射及对流引起的热损失的总和。计算热损失需要知道环境温度、风速及相对湿度或水蒸气分压。其它次要的热损失方式是     

Solar energy utilization for heating of indoor swimming pool

A simple transient analytical approach has been adopted for developing an explicit expression for the water temperature of an indoor swimmingpool coupled to a panel of collectors. For qualitative assessment of the analytical results, computations have been made for the winter climatic conditions of Sri Nagar, India. The effects of several parameters, viz. inlet temperature, heat removal factors, collector, etc. on the performance of the proposed systems have been studied in detail. It is observed that (i) the proposed model agrees with the experimental results of the Australian passive solar swimming pool and (ii) the desired temperature for the indoor swimming pool can be achieved by the active method.     

太阳能泳池加热工程实例介绍

一 前言 太阳能应用于游泳池水体加热是太阳能光热利用的新兴领域.此项技术一方面满足了社会快速持续发展、人民生活水平不断提高的实际需求,另一方面符合节约常规能源消耗、减少污染物及温室气体排放的政策导向,其发展前景十分看好.     

Performance analysis of a solar-assisted heat pump water heater

A modeling and system simulation of an integral-type solar assisted heat pump water heater (ISAHP) was carried out in the present study. The modeling and simulation assumes a quasi-steady process for all the components in the ISAHP except the storage tank. The simulation results for instantaneous performance agreed very well with experiment. The simulation technique was used to analyze the daily performance of an ISAHP for 1 year. It is shown that the daily total COP (COP_o) is around 1.7 to 2.5 year around for the ISAHP, depending on seasons and weather conditions. COP_o is higher than 2.0 for most of the time in a year and the daily operating time varies from 4 to 8 h. The online adjustment requirement of the expansion valve was also investigated using the present simulation technique. The analysis shows that the expansion device does not need to be controlled online. Using the 1-year simulation results, a universal daily performance correlation of the ISAHP was derived and shown experimentally to be applicable to another design of ISAHP.     

直膨式太阳能热泵系统性能分析及优化

直膨式太阳能热泵利用少量电能将太阳能的低品位能量转移至高品位,具有清洁、高效的优点,目前正成为节能领域的研究热点,近年来取得了飞速发展.国内外众多学者作了相关研究并取得了一定的成果.概述了直膨式太阳能热泵在国内外的研究进展,总结了内部参数和外部参数等方面对直膨式太阳能热泵系统性能的影响.针对不同的影响因素,给出了多种提高直膨式太阳能热泵系统性能的策略,以期对直膨式太阳能热泵的发展有一定的促进作用.     

Performance analysis of solar-assisted chemical heat-pump dryer

A solar-assisted chemical heat-pump dryer has been designed, fabricated and tested. The performance of the system has been studied under the meteorological conditions of Malaysia. The system consists of four main components: solar collector (evacuated tubes type), storage tank, solid-gas chemical heat pump unit and dryer chamber. A solid-gas chemical heat pump unit consists of reactor, condenser and evaporator. The reaction used in this study (CaCl2-NH₃). A simulation has been developed, and the predicted results are compared with those obtained from experiments. The maximum efficiency for evacuated tubes solar collector of 80% has been predicted against the maximum experiment of 74%. The maximum values of solar fraction from the simulation and experiment are 0.795 and 0.713, respectively, whereas the coefficient of performance of chemical heat pump (COP^h) maximum values 2.2 and 2 are obtained from simulation and experiments, respectively. The results show that any reduction of energy at condenser as a result of the decrease in solar radiation will decrease the coefficient of performance of chemical heat pump as well as decrease the efficiency of drying.     

Analysis of an open-air swimming pool solar heating system by using an experimentally validated TRNSYS model

In the case of private outdoor swimming pools, seldom larger than 100 m², conventional auxiliary heating systems are being installed less and less. Solar heating is an option to extend the swimming season. The temperature evolution of an open-air swimming pool highly depends on the wind speed directly on the water surface, which at the same time is influenced by the surroundings of the pool. In this paper, the TRNSYS model of a private open-air pool with a 50-m² surface was validated by registering the water temperature evolution and the meteorological data at the pool site. Evaporation is the main component of energy loss in swimming pools. Six different sets of constants found in literature were considered to evaluate the evaporative heat transfer coefficient with the purpose of finding the most suitable one for the TRNSYS pool model. In order to do that, the evolution of the pool water temperature predicted by the TRNSYS pool model was compared with the experimentally registered one. The simulation with TRNSYS of the total system, including the swimming pool and the absorber circuit integrated into the existing filter circuit, provided information regarding the increase of the pool temperature for different collector areas during the swimming season. This knowledge, together with the economic costs, support the decision about the absorber field size.     

A solar-assisted heat pump system for heating and cooling residences

A significant impact of solar energy applications on the total energy demand requires systems or devices which can be retrofitted to existing energy users. The all-electric residence unit, which includes about 10 per cent of all such units in the U.S.A. and constitutes over half of those completed in 1973, seems particularly suited to a solar modification. It is proposed that heating and cooling of the all-electric residence unit be accomplished by using a solar-assisted heat-pump system. The proposed system makes use of a conventional air-conditioning unit which would be modified by fitting controls to reverse the flow of refrigerant for the heating mode and by changing the outdoor heat exchanger from refrigerant-to-air to refrigerant-to-water. In addition, there would be provided a solar collector and two insulated water-storage tanks. Water from one tank would be circulated through the refrigerant-to-water heat exchanger when needed and then returned to the other tank, so that essentially a source of heat of constant temperature would be maintained, thus decreasing the temperature interval for the heat pump and thereby saving energy. In the cooling mode the stored water would be cooled by exposure of the solar collector to the night sky to decrease the temperature interval for the heat pump, thereby reducing energy consumption. Calculations were made for an existing residence unit for which the total energy input is known and to which the proposed solar-assisted heat-pump system is applied. An estimated cost of equipment and of its operation is compared with the cost of owning and operating fuel and electrically heated systems. It is concluded that the solar-assisted heat-pump system with current fuel prices can provide immediate economic benefit over the all-electric home and is possibly on par with residences using fuel oil or liquefied petroleum gas, but it yields higher cost over systems using natural gas. The effect of a two-phase expander to replace the expansion valve in the refrigerant circuit has been theoretically investigated. It shows a significant energy saving worthy of further economic and practical consideration.     

Performance assessment of hydrogen production from a solar-assisted biomass gasification system

In this study, we investigate a solar-assisted biomass gasification system for hydrogen production and assess its performance thermodynamically using actual literature data. We also analyze the entire system both energetically and exergetically and evaluate its performance through both energy and exergy efficiencies. Three feedstocks, namely beech charcoal, sewage sludge and fluff, are considered as samples in the same reactor. While energy efficiencies vary from 14.14% to 27.29%, exergy efficiencies change from 10.43% to 23.92%. We use a sustainability index (SI), as a function of exergy efficiency, to calculate the impacts on sustainable development and environment. This index changes from 1.12 to 1.31 due to intensive utilization of solar energy. Also, environmental impact of these systems is evaluated through calculating the specific greenhouse gas (GHG) emissions. They are determined to be 17.97, 17.51 and 26.74 g CO₂/MJ H₂ for beech charcoal, sewage sludge and fluff, respectively.     

Performance analysis of solar space heating system

The paper deals with solar space heating for a school during winter. The system, which is an extension of Solar Vapour Absorption Cooling Project, consists of coupling the solar collector field, the air handling units and the thermal energy reservoir in a single circuit with one pump. The analysis of the system has been done to describe the temperature history of the hot water reservoir as a function of two non-dimensional parameters. These parameters, which are functions of environmental and air handling unit characteristics, dictate the net thermal energy inflow or outflow from the reservoir. The problem solution has been obtained in a generalized form and predicted results are shown in dimensional form for the basic data chosen from an actual on-going project.     

The optical characteristics of swimming pool covers used for direct solar heating

Results are presented on the weathering of solar pool covers. Accelerated exposure in a Weatherometer enabled evaluation of the relative weathering of five commercial solar pool covers. Using the results of a series of tensile and elongation tests the order of relative protection against photodegradation was established. Correlation with natural weathering data enabled the acceleration factor to be determined and the minimum time to failure found.     

Economics of a solar-assisted heating/cooling system for an aquatic centre in a tropical environment

The paper reports on a feasibility study of a solar-powered heating/cooling system for a swimming pool/space combination in a tropical environment. The system employs an absorption chiller and a cooling tower to meet the locker-room load. The heating is accomplished by employing hot water generated by heat exchange with the solar collector working fluid. Two thermal storage tanks are employed for the collector and domestic use. The absorption chiller utilizes hot water to regenerate the LiBr solution. The proposed system will enable the swimming season to be extended from 16 weeks to 52 weeks. The economic analysis is performed based on the life-cycle-cost method. The effects of discount rate, fuel prices, and the fuel inflation rate are discussed. The analysis shows, with the present level of fuel prices, that the solarassisted system is not economical enough over a life cycle of 10 years. The study presents different scenarios for which the solar-assisted system is, however, economical.     

一种太阳能空气源/水源热泵系统的仿真分析

针对空气源热泵在低温环境下的低效问题与太阳能系统因依赖于天气状况而呈现的不稳定性等问题,提出了一种由太阳能水集热器、太阳能空气集热器、水源热泵和空气源热泵等4种装置组成的复合供暖、供热水系统,并根据日间与夜间的不同的气候条件,提出了5种运行模式。建立了系统的仿真模型,对系统在整个供暖季的运行仿真表明:该系统能够应对严寒天气并正常高效运转,在全供暖季的平均能效为4.21,各种工作模式的平均能效均在3以上,月平均能效为4~6。     

直接膨胀式太阳能热泵系统的理论分析

简述了直接膨胀式太阳能热泵的基本工作原理,从热力学理论出发,对直接膨胀式太阳能热泵的循环进行了理论热力分析,提出了系统各主要部件的能量平衡和火用平衡方程,分析了系统的性能系数COP和火用效率Eη。     

太阳能-土壤源热泵相变蓄热供暖系统运行模式

介绍了太阳能-土壤源热泵相变蓄热供暖系统;详细阐述了系统的各个运行模式;确定了模式间的转换条件.选取了供暖期间具有代表性的数据,分析了系统在不同供暖时期、典型天气的运行模式及运行效果.系统采用了太阳能和土壤热能的复合热源,增加了运行的灵活性,提高了运行性能系数.