الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 95 |  |  |
| | | from | 95 | | |
Abstract
A central challenge in cooling science nowadays is the development of thermally powered domestic scale chillers employing environmentally benign materials. The main challenge is to develop a device that is: environmentally friendly, virtually free of moving parts, highly reliable, capable of exploiting low-temperature waste heat, and highly efficient in converting the thermal energy into cooling effect .One of the promising candidates that has attracted the attention recently is the adsorption technology. from the above perspective, this thesis investigates the performance of a 2.5 kW adsorption chiller employing two beds. Lumped analytical modified model has been implemented to the main components of the chiller; including the bed, the evaporator, and the condenser. The main feature of the modified model is that the bed’s overall-heat-transfer-coefficient, as well as those of the condenser and the evaporator are no longer constants. They are calculated based on the variations of the geometric parameters and the operating conditions. The model implemented the mass and heat recovery while switching between the adsorption and desorption modes. All formulations are programmed using MATLAB in a way that can replace the adsorbent/adsorbate pairs to investigate and compare their performance. The effects of fins configurations on the chiller performance parameters in terms of coefficient of Performance (COP) and specific cooling capacity (SCC) are investigated. Four Cases for the adsorbent-bed configurations are investigated by varying heat transfer fluid (hot, cooling and chilled water) inlet temperatures, heat transfer fluid flow rates and cycle time and then the effects of these operating conditions together will be conducted on the best fin configurations. The heat transfer rate is enhanced while decreasing the fin spacing while thick fins have weak effect and, the increase of fin height reveals negative effect. The chiller performance is enhanced by changing the cycle time. The optimum range of the cycle time depends on the working pairs which is for silica gel-water pair is between 440 to 480 seconds and for activated carbon-ethanol is between 490 to 580 seconds. Increasing the regeneration temperature increases the cooling capacity with little reduction in the chiller COP. With optimum values COP value reaches 0.63 and SCC for silica gel 0.29 kW/kg reaches and for activated carbon 0.45 kW/kg. The comparison between the silica gel/water and activated carbon/ethanol systems reveals that the activated carbon/ethanol adsorption refrigeration system performs relatively better than the silica gel/water system.