| Abstract |
The air conditioning systems of low humidity applications using desiccant wheel consume a huge amount of energy to maintain the required low temperature and humidity needed by the application. In the mathematical work of the present study, proposed efficient systems that integrate the technologies of desiccant dehumidification, evaporative cooling, and freshwater production with the air conditioning system of low-humidity applications are presented. Thermodynamics analysis of the systems is conducted and the systems of governing equations are analytically solved and analyzed using EES software. Parametric studies are conducted to investigate the effects of the different operating parameters on the performance of the proposed systems. The power savings and the fresh water productions of the different proposed systems are evaluated and compared to select the optimum system configuration.
The results of the analytical study showed that :
(i) The fresh water production rate and the cooling coil capacity of the air conditioning system increase with increasing the fresh air ratio and outdoor humidity and decrease with increasing the ambient air temperature,
(ii) The saving in power consumption due to using energy recovery in system 2 and 3 remarkably noticed with increasing the outdoor air ratio.
(iii) The system with energy recovery located after the desiccant wheel is operating more efficiently and economically compared to the other systems.
An experimental investigation of the Humidification dehumidification (HDH) water desalination system using new air humidification section (honeycomb packed bed) and new dehumidification coils (un-finned and strips wired finned helical coils) at different orientations were conducted. HDH systems of different dehumidifying helical coils (finned and un-finned) were tested at different orientations (vertical and horizontal) for a wide range of air flow rate, air temperature, air humidity, water flow rate and water temperature.
The results of the experimental study showed that:
(i) The productivity and performance of the proposed HDH system increases with increasing the air flow rate, air humidity, air temperature, water flow rate and water temperature.
(ii) The proposed HDH system with the new humidification and dehumidification sections has better productivity and performance compared to other systems.
(iii) The dehumidifying finned helical coil always has better performance compared to the un-finned coils whatever the coil orientations, air flow rates, and air properties.
(iv) Placing the coil (finned or un-finned coils) at vertical orientation enhances the coil performance and the system productivity.
(v) The finned and un-finned coils at the vertical and horizontal orientations, the system productivity and the coil performance increases with increasing air flow rate, air humidity and air temperature.
(vi) The effect of using strip fins on the coil surface is more dominant in case of horizontal orientation of the coil compared to the vertical orientation. Finally, the results concluded the recommendation of using finned helical coils at the vertical orientation for the optimal performance of the HDH system.
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