Experimental Study On A Solar Driven Two-Rotor-Two-Step Desiccant Air Conditioning System

Desiccant cooling works in principle of desiccant cooling and evaporative cooling, and can handle the latent load and sensible load separately. The technology is advantageous as only water and moist air are involved in cooling process, and can be driven by low grade thermal energy resources, such as solar energy, geothermic energy and waste heat. In this thesis, by using of novel composite desiccant material, a novel two-rotor two-stage rotary wheel desiccant cooling system is proposed. The regeneration temperature of the system is low (50-90oC), meanwhile the thermal coefficient of the system is improved to 1.0. The result shows that compared with one-stage system, two-rotor two stage system has some notable advantages such as lower regeneration temperature and notable humidity removal capability.Based on the aforementioned work, a solar driven air conditioning system was built up inside an office building. The system comprised a two-rotor two-stage desiccant wheel air conditioning unit, a solar energy collector unit and a cooling tower water circulation set. It is shown that the moisture removal is about 6g/kg, the cooling power is between 10kW and 11kW, COP is about 1.0 under the typical summer condition. And 36.8% solar radiation energy is converted to 10.9 kW cooling power. Besides, detailed analyze on the supply air condition of the solar driven two-rotor two-stage desiccant wheel air conditioning system was undertaken. Performance of solar driven two-rotor two-stage desiccant wheel air conditioning system is compared with that of conventional vapor compression system. The data analyze indicates that with latent load of the fresh air undertaken by solar driven two-rotor two-stage desiccant wheel air conditioning system and sensible load of the recycle air covered by air source heat pump conditioner, 24.5% electricity consumption could be saved under system-collaborating condition.Analyze on the data indentified the area of the plat solar collector, about 36㎡. By modeling the performance of different shapes channel dehumidifiers under several typical conditions, found that the triangle shape dehumidifier with a 3.54 length-breadth-rate has the best performance. An analysis on the performance of different evaporative cooling styles for solar driven two-rotor two-stage desiccant wheel air conditioning system was made, recirculation evaporative cooling form was found to have the largest drop on supply air dry bulb temperature and avoid the humidification upon the supply air while that would cost some loss of the mass of supply air and system cooling power.