冷暖联供太阳能喷射制冷系统的一次能耗

太阳能喷射式制冷(热泵)系统在满足供冷、供热需求时，通常需要补充一定量的一次常规能源。该文在系统能量平衡的基础上，引入太阳能倍率、冬夏负荷比等参数，推导了太阳能制冷系统与电压缩制冷系统的一次能耗比计算公式。进而对太阳能双元混合工质喷射式制冷(热泵)系统、单元工质喷射式制冷系统、太阳能直接供热系统与电压缩制冷系统的一次能源消耗进行了对比分析。结果表明，太阳能喷射式热泵比太阳能直接供暖系统节约一次常规能源；太阳能喷射式制冷(热泵)系统，在其太阳能倍率位于节能区时，比电压缩制冷(热泵)系统节约一次常规能源。     

新型太阳能喷射与电压缩联合制冷系统研究

为提高太阳能与辅助能源的综合利用率，提出了一种新型的太阳能喷射式与电压缩式有机结合为一体的联合制冷系统，进而对这种新型联合系统及传统联合系统进行了热力学对比分析，对联合系统太阳能喷射式制冷时最佳发生温度进行了选择，并计算了典型年气象条件下两种联合系统相对于电压缩制冷系统的节能量及节能率。结果表明：两种联合系统相对于电压缩式制冷系统而言都是节能的，但新型联合制冷系统比传统联合制冷系统更节能，更能高效地综合利用太阳能与常规能源：在文中计算条件下，新型联合系统比传统联合系统多节能13．6％。     

新型太阳能喷射与电压缩式联合制冷系统的研究

提出一种新型的太阳能喷射与电压缩联合制冷系统,其既可以利用太阳能喷射式制冷又可以利用电能驱动压缩式制冷,可提高太阳能与辅助能源的综合利用率。对该系统中以R141b作为制冷工质,采用斜盘式压缩机的辅助电压缩制冷系统进行了理论循环计算与实验研究。实验表明,该辅助电压缩制冷系统的性能系数达到2.53。与传统的辅助能源应用方式相比,该辅助电压缩式制冷系统能更高效地利用常规能源,提高新型太阳能喷射制冷系统的综合节能效果。     

太阳能喷射式制冷系统性能分析

叙述了太阳能增压喷射式制冷的原理和系统工作过程. 探讨了太阳能喷射式制冷系统研究的进展状况.通过计算研究了多种制冷剂对喷射器工作性能和系统制冷系数的影响.应用数学模拟的方法,分析了太阳能增压喷射式制冷系统在实际日照条件下的工作性能.结果表明,这种系统能够利用太阳能提供实际需要的制冷量.     

太阳能喷射式制冷技术(上)

介绍了喷射式制冷的发展、工作原理和主要特点,并对单纯太阳能喷射制冷和压缩-喷射、吸收-喷射、吸附-喷射、热管-喷射等复合太阳能喷射式制冷系统进行了介绍和分析,并对其应用前景进行了总结.     

太阳能制冷讲座(12) 太阳能喷射式制冷技术(上)

介绍了喷射式制冷的发展、工作原理和主要特点,并对单纯太阳能喷射制冷和压缩-喷射、吸收-喷射、吸附-喷射、热管-喷射等复合太阳能喷射式制冷系统进行了介绍和分析,并对其应用前景进行了总结。     

太阳能驱动实现制冷的研究及其应用

本文提出了利用太阳能驱动实现制冷是一门节能环保技术，重点分析和论述了太阳能驱动实现制冷的几种主要方法．即利用太阳能光一电转换实现制冷、太阳能吸收式制冷、太阳能吸附式制冷和太阳能喷射式制冷。指出太阳能驱动实现制冷的研究具有广阔的应用前景。     

太阳能喷射式制冷系统性能的实验研究

对太阳能喷射式制冷系统进行了实验研究,采用电加热模拟太阳能辐射的方法,研究了冷凝器、发生器和蒸发器温度对制冷系统COP的影响,给出了太阳能喷射式制冷系统制冷能力与COP随时刻的变化关系。系统在80℃热源条件下,全天提供16℃的冷水,系统最大制冷量为0.43 kW。     

太阳能喷射式制冷技术进展

介绍了太阳能喷射式制冷的工作原理及系统构成,从制冷工质的选择、喷射器设计、系统运行参数优化及新型太阳能喷射式制冷技术四个方面,综述了太阳能喷射式制冷的发展,并简要地分析了太阳能喷射式制冷的发展前景.     

太阳能喷射制冷系统性能改善的方法分析

太阳能喷射式制冷循环，以其清洁元污染，系统运行和维护简单的优点，近年来吸引了很研究人员的关注，但系统性能系数偏低限制了它的发展。本文叙述了太阳能喷射式制冷的工作原理，并分别就太阳能集热器和喷射式制冷机，给出了它们的性能计算公式和方法。理论分析了太阳喷射式制冷系统性能改善的方法，并给出了几种实用的方案，可大大提高系统的工作性能。在此基础上，随着太阳能热利用技术的成熟，太阳能喷射式制冷有关广阔的发展前景。     

Energy balance of solar absorption and vapour compression cooling systems

Solar absorption cooling systems are viewed as potential alternatives to fossil-fuel-based conventional cooling systems. This view is investigated in this paper from the point of view of the energy balance of solar absorption and conventional systems. The paper investigates the primary energy needs of three cooling systems; dry and wet cooled vapour compression systems and wet cooled solar absorption. The sources of energy demand in the three systems are identified and their primary energy needs determined. The paper, then, investigates the conditions under which the energy inputs to the solar system breaks even with the other two systems. The investigation is conducted with particular reference to the operational and environmental conditions in Kuwait.     

Comparative study of different solar cooling systems for buildings in subtropical city

In recent years, more and more attention has been paid on the application potential of solar cooling for buildings. Due to the fact that the efficiency of solar collectors is generally low at the time being, the effectiveness of solar cooling would be closely related to the availability of solar irradiation, climatic conditions and geographical location of a place. In this paper, five types of solar cooling systems were involved in a comparative study for subtropical city, which is commonly featured with long hot and humid summer. The solar cooling systems included the solar electric compression refrigeration, solar mechanical compression refrigeration, solar absorption refrigeration, solar adsorption refrigeration and solar solid desiccant cooling. Component-based simulation models of these systems were developed, and their performances were evaluated throughout a year. The key performance indicators are solar fraction, coefficient of performance, solar thermal gain, and primary energy consumption. In addition, different installation strategies and types of solar collectors were compared for each kind of solar cooling system. Through this comparative study, it was found that solar electric compression refrigeration and solar absorption refrigeration had the highest energy saving potential in the subtropical Hong Kong. The former is to make use of the solar electric gain, while the latter is to adopt the solar thermal gain. These two solar cooling systems would have even better performances through the continual advancement of the solar collectors. It will provide a promising application potential of solar cooling for buildings in the subtropical region.     

Production of hydrogen for export from wind and solar energy,natural gas,and coal in Australia

Hydrogen production for export to Japan and Korea is increasingly popular in Australia. The theoretically possible paths include the use of the excess wind and solar energy supply to the grid to produce hydrogen from natural gas or coal. As a contribution to this debate, here I discuss the present contribution of wind and solar to the electricity grid, how this contribution might be expanded to make a grid wind and solar only, what is the energy storage needed to permit this supply, and what is the ratio of domestic total primary energy supply to electricity use. These factors are required to determine the likeliness of producing hydrogen for export. The wind and solar energy capacity, presently at 6.7 and 11.4 GW, have to increase almost 8 times up to values of 53 and 90 GW respectively to support a wind and solar energy only electricity grid for the southeast states only. Additionally, it is necessary to build-up energy storage of actual power >50 GW and stored energy >3000 GW h to stabilize the grid. If the other states and territories are considered, and also the total primary energy supply (TPES) rather than just electricity, the wind and solar capacity must be increased of a further 6–8 times. It is concluded that it is extremely unlikely that hydrogen for export could be produced from the splitting of the water molecule by using excess wind and solar energy, and it is very unlikely that wind and solar may fully cover the local TPES needs. The most likely scenario is production hydrogen via syngas from either natural gas or coal. Production from natural gas and coal needs further development of techniques, to include CO₂ capture, a way to reuse or store CO₂, and finally, the better energy efficiency of the conversion processes. There are several challenges for using natural gas or coal to produce hydrogen with near-zero greenhouse gas emissions. Carbon capture, utilization, and storage technologies that ensure no CO₂ is released in the production process, and new technologies to separate the oxygen from the air, and in case of natural gas, the water, and the CO₂ from the combustion products, are urgently needed to make sense of the fossil fuel hydrogen production. There is no benefit from producing hydrogen from fossil fuels without addressing the CO₂ issue, as well as the fuel energy penalty issue during conversion, that is simply translating in a net loss of fuel energy with the same CO₂ emission.     

Experimental performance evaluation of a novel heat exchanger for a solar hot water storage system

The performance of a novel heat exchanger unit (‘Solasyphon’) developed for a solar hot water storage system was experimentally investigated. The ‘Solasyphon’ is a simple ‘bolt-on’ heat exchange unit that can be integrated externally to a traditional single-coil hot water cylinder (HWC) avoiding the costly replacement of an existing HWC with a twin-coil HWC. The installation cost of a ‘Solasyphon’ is lower compared to a traditional HWC thus offers greater cost effectiveness. A data acquisition system was designed to compare the thermal performance of an integrated ‘Solasyphon’ HWC with a traditional twin-coil HWC under controlled simulated conditions. The analysis was based on experimental data collected under various operating conditions including different primary supply temperatures (solar simulated); primary supply patterns and draw off patterns. The results indicated that the ‘Solasyphon’ delivered solar heated water directly to the top of the HWC producing a stratified supply at a useable temperature. Under variable solar conditions the ‘Solasyphon’ would transfer the heat gained by a solar collector to a HWC more efficiently and quickly than a traditional HWC. The ‘Solasyphon’ system can reduce installation costs by 10–40% and has a lower embodied energy content due to less material replacement.     

Comparison of thermochemical,electrolytic, photoelectrolytic and photochemical solar-to-hydrogen production technologies

Hydrogen produced from solar energy is one of the most promising solar energy technologies that can significantly contribute to a sustainable energy supply in the future. This paper discusses the unique advantages of using solar energy over other forms of energy to produce hydrogen. Then it examines the latest research and development progress of various solar-to-hydrogen production technologies based on thermal, electrical, and photon energy. Comparisons are made to include water splitting methods, solar energy forms, energy efficiency, basic components needed by the processes, and engineering systems, among others. The definitions of overall solar-to-hydrogen production efficiencies and the categorization criteria for various methods are examined and discussed. The examined methods include thermochemical water splitting, water electrolysis, photoelectrochemical, and photochemical methods, among others. It is concluded that large production scales are more suitable for thermochemical cycles in order to minimize the energy losses caused by high temperature requirements or multiple chemical reactions and auxiliary processes. Water electrolysis powered by solar generated electricity is currently more mature than other technologies. The solar-to-electricity conversion efficiency is the main limitation in the improvement of the overall hydrogen production efficiency. By comparison, solar powered electrolysis, photoelectrochemical and photochemical technologies can be more advantageous for hydrogen fueling stations because fewer processes are needed, external power sources can be avoided, and extra hydrogen distribution systems can be avoided as well. The narrow wavelength ranges of photosensitive materials limit the efficiencies of solar photovoltaic panels, photoelectrodes, and photocatalysts, hence limit the solar-to-hydrogen efficiencies of solar based water electrolysis, photoelectrochemical and photochemical technologies. Extension of the working wavelength of the materials is an important future research direction to improve the solar-to-hydrogen efficiency.     

Solar energy outlook in Malaysia

Predicted to be the clean energy of tomorrow, solar energy has been in the forefront of energy development in many developed countries and a potential source of energy to developing countries like Malaysia. This paper presents Malaysia's solar energy or solar photovoltaic developmental outlook. The study is done by first looking into the country's energy policies related to solar energy. Key players in the solar energy development such as government institutions are introduced. Early solar energy programmes and a key project called Malaysia Building Integrated Photovoltaic (MBIPV) as well as its successful initiatives will be presented. Measures which have taken by the government of Malaysia including attractive incentives to encourage solar photovoltaic development, the country's potential in solar energy, foreign investments and future directions as well a feed-in tariff scheme will be presented in length to provide a broad spectrum of solar energy development in Malaysia. The outlook has been positive and the country is active in promoting solar as an alternative energy and is aware of benefits it will bring toward its economic development in the future.     

Development and assessment of a solar,wind and hydrogen hybrid trigeneration system

A solar-wind hybrid trigeneration system is proposed and analyzed thermodynamically through energy and exergy approaches in this paper. Hydrogen, electricity and heat are the useful products generated by the hybrid system. The system consists of a solar heliostat field, a wind turbine and a thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production linked with a hydrogen compression system. A solar heliostat field is employed as a source of thermal energy while the wind turbine is used to generate electricity. Electric power harvested by the wind turbine is supplied to the electrolyzer and compressors and provides an additional excess of electricity. Hydrogen produced by the thermochemical copper-chlorine (Cu-Cl) cycle is compressed in a hydrogen compression system for storage purposes. Both Aspen Plus 9.0 and EES are employed as software tools for the system modeling and simulation. The system is designed to achieve high hydrogen production rate of 455.1 kg/h. The overall energy and exergy efficiencies of the hybrid system are 49% and 48.2%, respectively. Some additional results about the system performance are obtained, presented and discussed in the paper.     

Complimentary nature of wind and solar energy at a continental mid-latitude station

Daily values of solar and wind energy have been used (i) to study renewable energy availability at various times of year, (ii) to test the level of persistence for inferences about the practicality of energy storage and (iii) to examine the complementary behaviour of these two daily time series on both seasonal and daily bases. Results for the station studied (central Iowa) show a bimodal distribution for winter solar energy, whereas non-winter solar and wind (all seasons) show unimodal distributions. Wind and solar energy were observed to be highly complementary on an annual basis, but only slightly complementary on a daily basis.     

Solar absorption cooling in Spain: Perspectives and outcomes from the simulation of recent installations

In spite of the fact that Spain is one of the EU countries with the highest solar resource on annual basis, the huge seasonal variation in solar radiation availability and the relatively short period with heating demand, make it difficult to reach significant contributions of solar energy to the buildings heating energy demand. This compromises the economic viability of big solar collector areas per capita, and introduces technical difficulties for the dissipation of the excess solar energy available in the summer months. On the other hand, in a large part of the Spanish territory, in other to reach adequate comfort conditions in our buildings, the energy demand for cooling is more important or of the same order than the heating demand. Cooling energy demand is now experiencing a fast growing rate as this comfort requirement becomes internalized. Domestic air conditioning equipments based on vapour compression cycles are being used to reach comfort conditions in some of the rooms of buildings that were designed without taking into account cooling requirements. In spite of their so far small contribution to the total building sector energy demand, these equipments are already imposing important constraints on the environment and the electricity distribution system. Solar absorption cooling arises as an interesting alternative, which at the same time allows reaching a higher solar contribution to the heating demand. However, solar cooling installations present several peculiarities with respect to the more known DHW or even heating installations, which require to incorporate a more detailed approach and additional considerations in the design and performance evaluation processes. Besides, some limitations still persist in solar absorption systems, which could make them loose their market potential for the benefit of other solar cooling options. In this paper, we present some conclusions arising from the experience gained in detailed TRNSYS dynamical simulation of some of the first commercial solar heating and cooling installations recently implemented in Spain, and analyse their perspectives in comparison with other solar cooling options.