Enhancing the amount of cold produced and saving of the required input heat using two different adsorbents together in the adsorption ice production AIP system
A theoretical investigation of the thermal performance (coefficient of performance COP and specific cooling power SCP) of a two bed Adsorption Ice Production AIP system based on the Silica gel-methanol as adsorbent- refrigerant in the first bed and activated carbon-methanol in the second bed is presented in this paper. Two fined-tube heat exchangers were designed (named SG-bed and AC-bed) in order to generate the same desorbed refrigerant amount of 1 kgmeth and to contain two different adsorbents. The mass transfer limitations from both the two beds and the heat transfer ability between the particles of adsorbents and heat exchanger fins are taken into account in the simulated model based on the linear driving force LDF model. To desorb 1 kgmeth from the SG-bed and AC-bed a cycle simulation computer program of the AIP system was developed to investigate the effect of desorption temperature Tdes, adsorption temperature Tads and the effect of difference of the required desorption/adsorption time on the system performance and on the amount of the ice produced per cycle mice. In the present simulations, the variation of the heat source temperature from 65 to 100 oC and chilled water temperature from 15 oC to 25 oC are taken. The results showed, that the AIP system attains a coefficient of performance COP of 66 % when the AC-bed is working and attains of 44 % when the SG-bed is working. The amount of the ice produced from the system estimated to 6kg per cycle (3 kg is produced from each of bed), but the Qin input energy required to activate the AC-bed has been saved by 46 % compared with that required to activate the SG-bed. Although each of the adsorbent beds was filled with different amount of the sorption material, it is found that the mass of the sorption materials inside the both beds has no effect on the cycle time but has important effect on the specific cooling power SCP. The cycle time is strongly dependent on driven temperature of heat exchange fluid, the design of the heat exchanger and the mass transfer coefficient of sorption material Dso. An experimental set up is planned to be built to make validation of the simulation results.