A SOLAR ASSISTED HEAT PUMP SYSTEM FOR DESALINATION

Abstract

Desalination is one of the most suitable fields for the utilization of solar thermal energy as the coincidence stands in many places of the world; on one side has water scarcity, on the other side seawater and solar irradiation is abundantly available. An integrated solar heat pump desalination system is developed at the NUS (National University of Singapore), which also has the opportunity of water heating and drying utilizing solar, ambient and waste heat from air-con which is conventionally dumped to the environment. The renewable energy is harnessed by three different type of collector, 1) Solar Evaporator Collector (SEC) which captures heat from radiation and ambient, 2) Liquid Solar Collector for pre-heating water for Desalination, 3) Photovoltaic system for running pump and blower. An efficiency equation is developed for SEC to correlate ambient and solar input and found the efficiency in the meteorological condition around 95%. In photovoltaic unit, three different types of cells: mono crystalline, poly crystalline and tandem was installed and their averages were found 10.4%, 9.5% and 8.8% respectively. The maximum Coefficient of Performance (COP) of the heat pump system was found 5.8. In integrated system, the maximum desalination production rate was found 9.6 kg/hr with Performance Ration (PR) of 1.2. Mathematical equations were developed for each component of the system, and a simulation program was then written. Comparison of the simulation and experimental results showed good agreement. To further analyze the behavior of the system, a parametric study was conducted.