Performance Analysis of a Combined Heat Pump- Dehumidifying System

During the past few decades, all Gulf States haveexperienced a rapid growth in living standard, which was naturallyassociated with rapid increase in demand for electricity and potablewater. Due to changes of living style, large portion of the electricpower was consumed for air conditioning (A/C). Lack of natural waterresources and striving needs for water made desalination the maintechnology to provide potable water. In an effort to search for a novelmethod for producing fresh water, the present paper investigates acombination of a heat pump (HP) with a dehumidification process toextract water from the atmospheric air. The unit supplies 1.586 m3/sair to an office building (250 m2 area) by the sea side in Jeddah,Kingdom of Saudi Arabia (KSA) where the average ambienttemperature is 34oC and relative humidity of 71%. The unit has twoseries evaporator-coils to maximize the water condensation process byreducing the air exit temperature to 8 oC.The performance of the combined HP-Dehumidifying unit hasbeen investigated for one year employing measured climaticconditions for representative days of the months. The maximum waterproduction was in September (2.23 m3/day) and the least was inJanuary (0.618 m3/day). The power consumed by the unit wasdetermined and the mean specific power rate was 0.42 kWh/liter offresh water. The pilot unit was purchased at a relatively high cost thatraises the fixed charges rate, the estimated maximum water cost was23 $/m3 for electricity rate of 0.045 $/kWh. A more realistic estimatebased on sharing the expenses between the A/C and water productionprocesses reduced the water cost to 13.5 $/m3 (50.6 Saudi Riyal/m3).The combined A/C- Dehumidifying unit can be efficient for resortareas of high humidity, low water demand and need for airconditioning.