Solar energy is a clean and renewable energy source, which produces neither greenhouse effect gases nor hazardous wastes through its utilization. Wide installation of renewable energy systems helps to keep our environment clean and healthy. World energy demand has been significantly increased in the last years due to the world economic growth and population increase, especially in developing countries. Conventional methods of generating electricity can produce pollutants such as carbon dioxide, the main gas responsible for global warming. The potential for reduction of greenhouse gases' emissions is an important issue for the wide spread of renewable energy systems. Greenhouse gases (GHG) that are most relevant to global warming are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The carbon dioxide (CO2) emissions resulted from fossil fuel resources need to be reduced substantially to prevent global warming. Conventional energy sources can damage air, climate, water, land and wildlife, landscape, as well as raising the levels of harmful radiation. As a consequence, there will be a need for development of large scale of a range of new technologies for conversion, storage, and efficient use of energy.
It is necessary to have air conditioning systems in hot climate areas like Kuwait. One does not feel comfortable if the temperature and humidity level is too high. A large amount of the operating costs of a building is determined by the energy requirements and the fuel consumption of its heating, ventilation, and air conditioning system (HVAC system). Active solar heating systems are now widely used in many applications, while active solar cooling systems are not. Numerous publications studied the performance of the solar heating systems (Lunde, 1978; Garg, 1987; Ghoneim et al., 1993; Bo Nordell and Hellström 2000; Mathioulakis and Belessiotis 2002; Thür et al., 2006; Oliveira, 2007). On the other hand, there are fewer publications discussing the performance of solar cooling and air conditioning systems.
I. Dincer et al. (eds.), Global Warming, Green Energy and Technology,
DOI 10.1007/978-1-4419-1017-2_28, © Springer Science+Business Media, LLC 2010
Absorption chiller systems are considered as the most suitable option for solar cooling because they are compact, reliable, and can be easily integrated into different building energy systems. An absorption air conditioner or refrigerator does not use an electric compressor to mechanically pressurize the refrigerant. Instead, the absorption device uses a heat source, such as natural gas or a solar collector, to evaporate the already-pressurized refrigerant from an absorbent/refrigerant mixture. Although absorption coolers require electricity for pumping the refrigerant, the amount is small compared to that consumed by a compressor in a conventional electric air conditioner or refrigerator. It is more economical to use a solar system for both heating and cooling purposes, because implementing solar space cooling systems alone is quite expensive. Significant space heating and/or water heating can be accomplished with the same equipment used for the solar cooling system.
Lof and Tybout (1974) made an extensive study of solar heating and cooling systems for eight cities in the USA. The system has been optimized to minimize the annual energy cost. The performance of solar heating and cooling system has been studied by Nakahara et al. (1977). Their results showed that the system was able to provide all the required heating energy in the winter and 70% of the energy needed to drive an absorption chiller on a typical summer day. In Saudi Arabia, a 3.5 ton lithium bromide-water absorption chiller (LiBr-H2O) system with flat plate collectors was installed and tested by Sayigh and Khoshaim (1981). Van Hattem and Dato (1981) conducted an experimental study of a solar-powered cooling system in Ispra, Italy. The overall cooling efficiency (the ratio of cooling load to total solar energy) was found to be around 11%. The feasibility of utilizing solar energy for comfort cooling in Hong Kong has been studied by Yeung et al. (1992). The system has an overall efficiency of approximately 8% and an average solar fraction of 55%.
Bruno et al. (1996) integrated an absorption chiller in a combined heat and power plant. They concluded that the absorption chiller is economically viable with the gas turbine when the chiller is used to cool the inlet air to the turbine to increase generator capacity. The half-effect absorption unit can also be used in applications where the heat source temperature is too low to be used to fire a single-effect unit (Bruno et al., 1996). Furthermore, natural night ventilation appears to be much more effective than an earth-to-air heat exchanger to improve comfort. Gordon and Choon (2000) claimed that solar mini-dish systems are able to realize net COPs of around 1.0. A further boost in net COP to around 1.4 can be achieved by modifying the conventional scheme to a thermodynamic cascade that takes maximal advantage of high-temperature input heat. The compactness and modularity of solar mini-dish systems opens the possibility for small-scale ultra-high-performance solar cooling systems.
Ciampi et al. (2003) presented an analytical method for the calculation of the energy saving achievable by using ventilated facades in which the air flow inside the air duct is due to stack effect. The influence of the variation of some quantities necessary for calculation on the energy performance of ventilated facades is investigated. In particular, the energy performance of such facades results to be strongly influenced by the air duct width, the insulating material distribution, the solar radiation intensity, the wall outer surface thermal resistance, and the roughness of the slabs delimiting the air duct.
Breesch et al. (2005) studied passive cooling in a low-energy office building in Belgium in which natural night ventilation and an earth-to-air heat exchanger are applied. The overall thermal comfort in the office building is evaluated by means of measuring and simulation results. The evaluation shows that passive cooling has an important impact on the thermal summer comfort in the building.
A mathematical and numerical models were developed by Mesquita et al. (2006) for internally cooled liquid-desiccant dehumidifiers, using three different approaches. The variable thickness model results closely matched the experimental data available in the literature. Belarbi et al. (2006) proposed a cellular approach in which the spray is considered as a pile of rigid spheres of equal size; each sphere has multiple layers and contains a drop in its center. Their parametric studies showed the influence of each variable on the evaporation time of the droplets. The model can be used for sizing passive evaporative cooling systems and towers for buildings using the passive evaporative.
The first goal of this study is to investigate the thermal performance and the feasibility of solar system designed for space heating, domestic water heating, and cooling requirements of a typical house in Kuwait. The single-effect lithium bromide-water (LiBr-H2O) absorption chiller model is based on a commercially available LiBr-H2O absorption chiller, Arkla model WF-36. The Arkla chiller has a nominal cooling capacity of 3 ton (37,980 kJ/h). In this work, transient simulation program, TRNSYS (1993) is adapted to simulate the thermal performance of different solar heating and cooling system components. The economic calculations for this study are based on life cycle savings (LCS) method (Duffle and Beckman 1991). The second purpose of this work is to assess the environmental impact of the solar heating and cooling system in Kuwait climate. The environmental impact is assessed by evaluating the annual avoided CO2 emission attained and the reduction cost achieved when the conventional energy sources are replaced by solar heating and cooling systems.
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.