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REFRIGERATION USING SOLAR ENERGY1
Transcript of REFRIGERATION USING SOLAR ENERGY1
TEJBIR SINGH-2K10/EC/147 JAIDEEP SINGH-2K10/ME/055
DIVYANSHU SETH-2K10/ME/047 ABSTRACT ABSORPTION refrigeration: In this system solar energy is used to drive out the volatile component from a solution and build up the pressure. Examples are water vapour from lithium bromide water solution or ammonia from aqueous ammonia solution. The vapour is then condensed (rejecting heat). This is done with either water-cooling or air-cooling. The condensed liquid is then expanded to absorb heat from the space where refrigeration is needed. The vapours are once again absorbed in the solution. The cycle is continuously repeated. Sub zero temperatures can be reached by absorption refrigeration systems. Ice can be made. BASICS The adsorption process concerns separation of a substance from one phase, accompanied by its accumulation or concentration on the surface of another. On the other hand, absorption is the process in which material transferred from one phase to another, (e.g. liquid) interpenetrates the second phase to form a solution. In general, The main differences between absorption and adsorption are located in the nature of the sorbent and the duration of the sorption cycle, which is significantly longer for adsorption The phenomenon of absorption is the mixture of a gas in a liquid, the two fluids
presenting a strong affinity, to form a solution. This process is reversible. One can
describe the principle of a simple effect system with H2O–LiBr as working pair.
1. A pump brings the rich solution towards the high-pressure zone.
2. The mixture is heated in the generator. A contribution of heat (waste heat, solar energy)
allows the separation of the refrigerant (H2O) from the absorbent (LiBr solution).
3. The vapors of refrigerant are sent towards the traditional cycle of condenser, expansion
valve and evaporator. Cold is produced by the evaporation of refrigerant in the
evaporator at low pressures.
4. The poor solution turns over in the absorber by passing by a pressure-relief valve.
5. The vapors of refrigerant are absorbed by the poor solution of absorber coming from
the generator. The cycle can start again. ABSORPTION REFRIGERATION ` Hot water Cooling water
(driving heat) condensor evaporator absorber generator Schematic drawing of an absorption chiller Two major working pairs used in the solar absorption refrigeration systems are H2O–LiBr and NH3–H2O. H2O is refrigerant and LiBr is absorbent in the former system, oppositely NH3 is refrigerant and H2O is absorbent in the latter case. The basic operation of an ammonia-water absorption cycle is as follows. Heat is applied to the generator, which contains a solution of ammonia water, rich in ammonia. The heat causes high pressure ammonia vapor to desorb the solution. solar heat, The high pressure ammonia vapor flows to a condenser, typically cooled by outdoor air. The ammonia vapor condenses into a high pressure liquid, releasing heat which can be used for product heat, such as space heating. Absorption cycles can produce a variety of thermal outputs. In common commercial use today are gas-fired absorption chillers, which produce chilled water for space cooling applications. The absorption cycle can produce low temperature cooling for ice production or cold storage. Turbine inlet cooling is a very efficient use of absorption cooling, boosting turbine efficiency by up to 15%. Many other applications exist in industry, where waste heat is available and cooling is required. Advanced cycles can also produce electrical or shaft power by producing steam or high pressure vapor to power a turbine/generator pair. 1. Absorption Liquid Chillers, Form 155.16-EG, York Division, Borg-Warner Corporation, York, Pennsylvania.
2. Best R., Ortega N. Solar refrigeration and cooling. In: World Renewable Energy Congress V, Florence, Italy
3. Research Article - Performance Prediction of Solar Adsorption Refrigeration System by Ann V. Baiju and C.Muraleedharan
4. Dai YQ. Technology and Application of LiBr absorption refrigeration. In: China: Chinese mechanical engineering industry publication,
5. Computer Based Thermodynamic Properties of Ammonia-Water Mixture for the Analysis of Power and Refrigeration Cycles by K. Sadhukhan, A. K. Chowdhuri and B. K. Mandal (Department of Mechanical Engineering Bengal Engineering and Science University, Shibpur)
6. Experimental Study of a Solar Adsorption Refrigeration Unit, Factorial Analysis Ghassan M. Tashtoush*, Bourhan M. Tashtoush, Mustafa M. Jaradat Mechanical Engineering Department, Jordan University of Science and Technology, Irbid, Jordan
7. Review of solar sorption refrigeration technologies: Development and applications by Y. Fan, L. Luo, B. Souyri
8. Refrigeration using solar energy- survey by APITCO consultancy services, India.
9. Solar Refrigeration By Sanford A. Klein, Ph.D., Fellow ASHRAE, and Douglas T. Reindl, Ph.D., Member ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org)
10. Solar Thermal Cooling, WEST CENTRAL RESEARCH & OUTREACH CENTER RENEWABLE ENERGY PROGRAM
11. ADSORPTION REFRIGERATION - AN EFFICIENT WAY TO MAKE GOOD USE OF WASTE HEAT AND SOLAR ENERGY
R. Z. Wand and R. G. Oliveira Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University,
12.THE USE of DIRECT SOLAR ENERGY in ABSORPTION REFREGERATION EMPLOYING NH3 – H2O SYSTEM Prof. Dr. Adel A. Al-Hemiri and Ahmed Deaa Nasiaf Chemical Engineering Department, College of Engineering, University of Baghdad, Iraq Articles and Research Papers Read by the Group ADSORPTION REFRIGERATION Adsorption is the general phenomenon resulting from the interaction between a solid (adsorbent) and a gas (refrigerant), based on a physical or chemical reaction process. An adsorption refrigeration machine utilizes the phenomenon of physical adsorption between the refrigerant and a solid adsorbent; the molecules of the refrigerant come to be fixed at the surface of adsorbent
Commercially available adsorption chillers typically use water as the refrigerant and a desiccant (drying agent) like silica gel or zeolite as the adsorbent. The adsorption chiller consists of four main components:
2. Evaporator, and
3. Two desorbing/adsorbing chambers. Water vapor is condensed by rejecting excess heat to a cooling tower. The resulting liquid water flows into the evaporator The water vapor is adsorbed in the second adsorbing chamber. During the adsorption process heat is being produced, which also has to be removed by the cooling tower. The adsorbent (silica gel) is dried out by applying heat from solar heated water. Vapor is generated and flows into the condenser. When the material is sufficiently dried out, the heat input into the adsorbing chamber stops. In the low pressure of the evaporator, water is induced to boil by the attraction of the desiccant
in the second adsorbing chamber. This cools the water in the evaporator which is
used to provide chilled water for air conditioning Adsorbents are materials possess a permanent porous structure that, at low temperatures, acts like a sponge, soaking up or adsorbing the methanol (the refrigerant). As the temperatures elevated, the refrigerant released or desorbed. This adsorption cycle is silent in operation and most suited for remote locations without electricity sup- ply since they can be powered by purely thermal energy like solar energy.In the Solar adsorption system the adsorbent packed in a sealed collector painted black to enhance the solar radiation ab- sorption. The solar energy heats the high concentration of adsorbent and container to the maximum cycle tempera- ture during the day time where the refrigerant starts de- sorbing from the adsorbent. OUR PROJECT The low temperature application like food storage will be used. As a matter of fact, these technologies are attractive for refrigeration purpose in remote or rural areas of developing countries where the access to electricity is difficult. FOR EXAMPLE, WALMART is now expanding in India and they need cold storages in rural areas. it would be in our best interest that these cold storages are ECO-FRIENDLY. This will be achieved by using solar refrigeration technologies. For places where sunlight is abundant we will use absorption otherwise adsorption will be used.