On the dimensional analysis for solar desalination using humidification-dehumidification processes

This letter discusses the model for solar desalination productivity proposed in the paper ‘‘Solar desalination using humidification–dehumidification processes. Part II. An experimental investigation’’, [Energy Conversion and Management, 45 (2004) 1263–1277] by Nafey et al. (2004). In their study, the dimensional analysis is used to deduce the model, and the physical variables considered include the total solar energy incident through day, energy of water input to unit, energy of air input to unit, air flow rate, feed water flow rate, productivity, cooling water flow rate, average inlet temperature of cooling water, average water inlet temperature to water heater, average air inlet temperature to air heater, average ambient temperature through day and average wind speed through day. It is found that there are some mathematical issues should be improved in the derivation processes. Since Nafey’s paper has been a well-cited publication on solar humidification-dehumidification desalination and often serves as a reading to newcomers in this field, this letter aims to rectify the issues and to provide a complete derivation.