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Solar Driven Absorption System Seminar Report

The solar-powered air-conditioning systems have been in an intensive development for the last few years and are considered as the most viable application for the thermal solar systems in the regions of world. This is mainly due to the increasing higher electrical consumption in many countries due to expanding usage ofcooling systems during the summer months.

In this seminar a triple-state LiCl–H 2 O absorption system with a power of 10 kW that is fully driven by solar thermal energy has been designed and installed in a detached house in Spain. Theheat dissipation of the system takes place through a swimming pool, which avoids the need for a cooling tower. The system is fed using a solar thermal system with an area of 35.54 m 2 . The system behavior was monitored for a full year. The design and thecalculations for the thermal requirements are presented, and the values of the coefficient of performance (COP) and the expected temperatures are compared with those obtained experimentally. This seminardemonstrates that the actual values are slightly lower than the simulated values. The experiment has validated the possibility of using a swimming pool as a sink for heat dissipation. The economic analysisshows that the internal rate of return (IRR) reaches 12.45% while achieving a 68% reduction in greenhousegases (GHG) emissions. The results show that this approach can add great value to solar thermal energysystems and also help in tackling the problems related to high temperatures during the summer months.

Continuing increase in the global electricity demand and depletion of fossil fuel resources have necessitated a paradigmshift in the development of eco-friendly and energy-efficient technologies .Global energy consumption has been growing as a result ofincrease in the population and increased energy demand fromemerging countries. High energycosts add to the loss of competitiveness in countries, andthe economic consequences are worsening.

The world energy use is rapidly growing at an alarming rate. This has already raised concerns over potential supply difficulties, depletion of energy resources and expediting environmental impacts (ozone layer depletion, global warming, climate change, etc.). The global raising pattern in buildings energy consumption,both residential and commercial, has climbed steadily; reaching figures between 20% and 40% in developed countries. In fact, ithas exceeded the other major sectors, namely, industrial and transportation.Key reasons attributing to this increasing figure include:
(1) growth in population;
(2) greater demand for building services;
(3) the need for better comfort levels;
(4) longer duration of occupants spent time inside buildings. Without a doubt, the upraising trend in energy demand will continue into the future. For this reason, improving energy efficiency in buildings is todaya prime objective for global energy policy makers. Many energy policies and strategies to reduceCO 2 climate change emissions are addressed to decreasing buildingenergyconsumption. Passive solar architecture of buildings isincreasing in popularity as an intelligent way to design andconstruct more energy-efficient buildings as well as to increaseindoor comfort .Further reductions in energy consumption,energy costs and CO 2 emissions of buildings can be achieved byadopting active technologies such as solar photovoltaic arrays andsolar thermal collectors .In the recent years, research has been devoted to improving thevapour absorption system. Solar cooling has been shown to be technically feasible. It is particularly attractive application forsolar energy because of the simultaneous peak in cooling loadswith the availability of solar power. Secondly, mechanical vapourcompression cycles require high amounts of energy for theiroperation. Apart from this, recent studies have shown that theconventional working fluids of vapour compression systems arecausing ozone layer depletion and green house effects. Howevervapourabsorption systems harness inexpensive heat, solar,biomass or geothermal energy sources for which the cost of supplying is negligible in many cases. Moreover, the working fluidsof these systems are environmentally friendly.Summer air-conditioning is significantlycontributing to the peak electricity demand, affecting the cost of maintaining a reliable electricity supply, and hence remainsa challenging problem. Among possible solutions is the use of renewable energy sources, of which solar energy is verypromising as it is abundantly present and environmentally sustainable.

Solar thermal energy can be easily integrated into buildings and is usually required by energy regulations. The technologies available on the market for cooling via solar thermal energy include absorption, solid and liquid desiccant, and solid adsorption machines.Absorption cycles have been an economical and energy-competitive system that can be usedto drive single-effect absorption systems in buildings. These advantagesmake Vapour absorption system(VAC) attractive from both the energy and theenvironmental impact points of view, although the integration ofthis technology into houses is problematic, especially from thestandpoint of heat dissipation. This seminar presents a study of anactual installation of a triple-state LiCl–H 2 O VAC system, fullydriven with solar thermal energy (STE) that is integrated into ahouse and uses a swimming pool as a sink for heat dissipation.There have been previous reviews of the state-of-the art in solartechnology for absorption systems, but typically, the focus hasbeen on LiBr–H 2 O systems. Double-effectcycles cannot be easily integrated into small buildings due to hightemperature requirements. Energy storage is an importantdesign issue because of the need to couple cooling demand andsolar thermal production. Cold energy and thermal energy can bestored using sensible latent or thermo-chemical energy storage.A LiCl–H 2 O system allows thermo chemical storage in the systemitself, making this solution optimal for building integration and forsolar thermal energy use. The energy storage system allows bettersatisfaction of cooling demand by using the energy storage inthe absorption machine without the use of cold-water reservoirs.However, no experimental analysis has been carried out into howthese systems can be integrated into buildings. The paper authorsanalyzed the theoretical and the actual energy efficiencies of a triple-state absorption system, but there have been no experimentalstudies of the performance of LiCl–H 2 O-type systems for atypical year of operation. The experimental system studied, whichincludes a triple-state LiCl–H 2 O machine and uses a swimming poolas a heat sink, is highly novel. This paper discusses the actual coefficient of performance (COP)of the installation during operation in the summer months andaddresses the variation observed in the COP compared to the predicted value. Finally, the feasibility of integrating this technology into homes is assessed, and areas forimprovement are identified.

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