Entropic analysis of adsorption open cycles for air conditioning. Part 2: interpretation of experimental data

The full second-law analysis, developed in Part 1 (M. Pons and A. Kodama, I nt. J. Energy Res. 2000; 24: 251-262) is applied to experimental results. T hat approach takes into account the irreversibilities due to the open chara cter of the cycle. Measurements are performed on a solid desiccant cooling unit operated in the ventilation mode. Experimental data permit us to estab lish the entropy balance of the unit. The results show that the sum of all the considered entropy productions completely explain the difference betwee n the Carnot COP and the actual COP of the unit. The effects of three exper imental parameters are investigated: the rotation speed of the dehumidifier (desiccant wheel), the air velocity and the regeneration temperature. Expe rimental results show that there exists an optimal rotation speed which res ults from a combination between the different entropy productions in the cy cle. When the air velocity is increased, together with an accordingly optim ized rotation speed, the cooling capacity increases while the COP decreases due to increases in the entropy productions in the dehumidifier and sensib le heat exchanger. Moreover, it appears that the most significant entropy p roductions take place in the dehumidifier and heating system. In the invest igated experimental unit, these two entropy productions have similar magnit udes. However, when the regeneration temperature is increased, the irrevers ibilities due to mass exchanges with outside air become comparable to these and surely should not be forgotten in a global optimization of the process . The present analysis is a solid basis for reducing the largest entropy pr oductions thus optimizing the process. Copyright (C) 2000 John Wiley & Sons , Ltd.