t5.3.O5

SIMPLIFIED ANALYSIS OF COUPLED HEAT AND MASS TRANSFER PROCESSES IN AN

OPEN CYCLE SOLAR C/R

Li Yutong

Renewable Energy Research Group (RERG), The Hong Kong Polytechnic University,

Hung Hom, Hong Kong

Yang Hongxing Renewable Energy Research Group (RERG), The Hong Kong Polytechnic University,

Hung Hom, Hong Kong

behxyang@polyu.edu.hk

ABSTRACT

Application of the open cycle solar collectors/regenerators (C/R) is an effective way to utilize low-grade solar thermal energy to concentrate desiccant solution for air-conditioning. This paper aims at developing an analytical model for the coupled heat and mass transfer process inside an open cycle solar C/R. Within narrow range of operating conditions, linear approximations were made to find the dependence of equilibrium humidity ratio on the solution temperature, constant properties and coefficients. New parameters, which represent the heat and mass transfer driving forces, were defined and the basic differential equations were rearranged to obtain two coupled non-homogeneous linear equations. The effects of the climate conditions were organized as non-homogenous parts, which allow direct evaluation. The analytical expressions for water evaporative rate and outlet conditions

of the desiccant solution and scavenge air were further developed based on the analytical solution. A parametric analysis of the solar C/R has been performed to reveal the effects of climate conditions and system variables on the rate of evaporation of water from the solution. The ratio of the solution to the air mass flow rate was also found to be an important controlling parameter. Based on the simulation results, the possible optimization methods for the solar C/R and operating variables were also discussed. 1. INTRODUCTION

Dehumidification for air conditioning is traditionally accomplished with vapor compression equipments. The disadvantage of this air handling process is that the temperature of the air must be cooled below its dew-point which is deemed to be energy expensive [1]. An open cycle liquid desiccant dehumidification system driven by solar energy was emerged as a potential alternative to conventional vapor compression system for air conditioning. This system can utilize solar energy and can possibly provide cooling more efficiently. Additional advantages are more precise humidity control and possible anti-bacterial effect [2][3][4]. The open cycle solar collector and regenerator (C/R), where the desiccant solution is heated and concentrated, is an important part of this system. The schematic diagram of the open cycle solar C/R is shown in Figure 1. It composes of glazing cover,

t5.3.O5

Fig. 1: Schematic graph of the open cycle solar collector and regenerator.

相关推荐
相关主题
热门推荐