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Fixed-plate exchangers
Fixed plate heat exchangers, commonly known as air-to-air heat exchangers, can reduce laboratory energy consumption. The transfer of waste energy from exhaust to laboratory make-up air depends on the location and characteristics of the air streams. These air streams are separated by plates, which are usually augmented with fins. The heat exchange principle is simple: warm exhaust air heats a fixed plate, which, in turn, heats the cool make-up air on the other side of the plate. This exchanger uses no transfer media other than the plate-forming wall of the exchanger

Why I prefer PLATE over WHEEL
1-There is a cross leakage in energy recovery wheels.Cross leakage through the energy recovery wheels ranges from 2% to 5% between the supply and exhaust air streams . In many applications (especially where odors, pathogens or other harmful pollutants are present), it is clearly unacceptable for exhaust air (EA) to leak into the outdoor air (OA) or fresh air stream being furnished to the conditioned space.I don't want to give air form toilettes to dining room .Some standart give permission to toillettes air but I don't !!!
2-The remedy applicable to wheel systems is to increase OA airflow thereby pressurizing this air stream. As long as this pressure gradient is maintained, the majority of the leakage is from OA to EA, thus reducing, if not eliminating the exhaust air transfer. This imbalance can represent a substantial inefficiency, e.g. 700 CFM of OA may be required to provide 500 CFM to the conditioned space. It is not uncommon for “lost air” to account for 25-30% of a wheel’s rated airflow.
3-Power consumption:A dedicated motor is required for rotation of the wheel. For systems installed in cold-weather climates, an effective defrost mechanism will require yet another draw on available power. PLATE HEAT EXHANGERS has no moving parts at all.
4-Maintenance is generally acknowledged as the real Achilles’ heel of wheel systems. Wheel-type ERV is perhaps the least forgiving of all HVAC equipment. If not properly serviced, it will fail – often within a few years of installation. Routine maintenance generally requires disassembly of the unit, cleaning/reconditioning of the wheel, re-assembly and re-calibration of the mechanicals. This is a time-consuming and costly process requiring the attention of a trained technician. In addition, during the maintenance process, no energy recovery takes place, i.e. the heating or cooling equipment must work to condition raw, outside air.

Air to air plate heat exchanger selection software (from HOVAL)




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