vapourises , moving heat to the reheat section ( downstream from the cooling coil ). Since heat has been removed from the air before the cooling coil , air passing through the cooling coil drops to a lower temperature , resulting in more condensate removal . The over cooled air is then reheated to a comfortable temperature and a lower relative humidity by the reheat section , using the same heat originally absorbed by the first section . The result is an air conditioning system with the ability to remove 50 to 100 % more moisture .
Picture 11 : AHU with Double Chilled Water Coils and Heat Pipe Wrap Around Coil
Chilled Water Coil Direct Expansion ( DX ) Hybrid System
Figure 2 : How to condition the 100 % fresh air to supply to OT room at 18 ° C , ± 50 % Relative Humidity ( RH )
Picture 12 : Wrap Around Heat Pipe section drawing
because of vapour pressure . On the cold side the refrigerant condenses and then flows back . It ’ s really that simple .
The wrap around heat pipe is a pipe wrapped around a cooling coil and consists of two sections , the precool ( evaporator ) section placed before the cooling coil and the reheat ( condenser section ) placed after the reheat coil .
The precool section is located on the incoming air stream before the cooling coil . When warm air passes over the first section , the liquid refrigerant
Stage 1 in the system involves cooling ambient heat of 100 % fresh air , at 34 ° C Dry Bulb ( DB )/ 28 ° C Wet Bulb ( WB ), to 12 ° C dew point , where the relative humidity ( RH ) is 100 %, and the moisture content is 8.5g / kg . This cooling process involves designing a minimum six row chilled water coil where the supply chilled water is at 5.6 ° C / 12.2 ° C . Although an eight row or more chilled water coil can provide an exit temperature down to 8 ° C to 10 ° C , this gives rise to maintenance issues , as more rows provide greater challenges in cleaning the inner part of the coils . If this is not done effectively it will result in choked coils and the performance of the Chilled Water Coil will drop tremendously . The better approach is to use two chilled water coils placed side by side .
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