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Transient performance analysis and investigation of three proposed solar powered humidification–dehumidification (HDH) water desalination systems: single stage (SS), double stages (DS) and modified double stages (MDS) systems are presented for hot and humid cities. Open/closed modes of operations of the systems are also investigated. A parametric study of the hourly and daily systems performance is presented at various operating parameters. The results reveal that: (i) inserting solar collectors in HDH systems for air and water heating substantially enhances the system’s performance; (ii) the fresh water productivity of all systems at open mode of operation increases with increasing the outdoor air temperature and humidity; (iv) at low outdoor humidity, the system’s performance at closed mode of operation is higher than those at open mode of operation and the opposite is true at high outdoor humidity; (v) comparing between the three systems, MDS system (open mode) can produce fresh water of 350 kg/day with GORday of 1.63 and its fresh water productivity enhances with 86.7% and 34% than SS and DS systems, respectively; and (vi) using control system, the performance of the proposed systems can be maximized by changing between the open/closed mode of operations according to the outdoor conditions.

A low energy HDH (humidification-dehumidification) and AC (air-conditioning) hybrid system using an efficient design of dehumidifier (strips-finned helical coil) and packing pad material (cellulose paper in bee-hive structure) is proposed. An experimental investigation of the performance of the proposed system is conducted for wide ranges of air and water flow rates and temperatures and packing pad thickness. The results showed that (i) the proposed hybrid system can produce fresh water and remove space cooling load to maintain the required comfort conditions, (ii) the fresh water production rate, cooling load capacity and the system performance increase with increasing air and water flow rates and temperatures and cooling pad thickness, (iii) the proposed HDH system with the new humidification-dehumidification sections has better productivity and performance compared to other systems, (vi) daily production cost of the system increases with increasing inlet air and water flow rates and decreasing cooling pad thickness and air and water temperatures, and (v) production cost per kg of fresh water decreases by increasing cooling pad thickness and air and water flow rates and temperatures. The system performance parameters (fresh water productivity, cooling load capacity, space supply air temperature and coefficient of performance) can reach to 17.42 kg/h, 3.9 kW and 16 °C, and 4.35, respectively. Moreover, the lowest specific cost of fresh water production can be obtained is 0.7 ¢/kgFW, respectively. Finally, empirical correlations of system productivities and performance parameters in terms of operating conditions and system geometric parameters were predicted within acceptable errors.

Theoretical investigation on the performance of a proposed innovated solar integrated system for air conditioning (A/C) and humidification dehumidification (HDH) water desalination in hot and humid regions is presented. Transient analysis and parametrical study for the system are conducted under different operating and design conditions. System performance parameters (fresh water production rate, cooling capacity, electrical power consumption, water recovery and system coefficient of performance) are hourly estimated and daily integrated for different operational and design conditions. The results reveal the increase of fresh water productivity, system water recovery, cooling capacity, electrical power consumption and COP of the system with the increase of air temperature, air humidity, and solar collectors area. For system assessment, the system performance parameters are compared with the performance of a basic system under the same conditions. Cost saving analysis showed the proposed system operates more economically and efficiently that in hot and humid climatic areas. General numerical correlations for system performance parameters are proposed in terms of the design and operational conditions.

Performance of integrative air-conditioning (A/C) and humidification–dehumidification desalination systems proposed for hot and dry climatic regions is theoretically investigated. The proposed systems aim to energy saving and systems utilization in fresh water production. Four systems with evaporative cooler and heat recovery units located at different locations are proposed, analyzed and evaluated at different operating parameters (fresh air ratio, supply air temperature and outside air wet bulb temperature). Other two basic systems are used as reference systems in proposed systems assessment. Fresh water production rate, A/C cooling capacity, A/C electrical power consumption, saving in power consumptions and total cost saving (TCS) parameters are used for systems evaluations and comparisons. The results show that (i) the fresh water production rates of the proposed systems increase with increasing fresh air ratio, supply air temperature and outdoor wet bulb temperature, (ii) powers saving of the proposed systems increase with increasing fresh air ratio and supply air temperature and decreasing of the outdoor air wet bulb temperature, (iii) locating the evaporative cooling after the fresh air mixing remarkably increases water production rate, and (vi) incorporating heat recovery in the air conditioning systems with evaporative cooling may adversely affect both of the water production rate and the total cost saving of the system. Comparison study has been presented to identify systems configurations that have the highest fresh water production rate, highest power saving and highest total cost saving. Numerical correlations for fresh water production rate and total system energy consumption are developed and presented in terms of the controlling parameters.