Defrost
In cold stores, the accumulation of frost formation on the evaporator tube reduces air velocity and hence the intensity of heat transfer significantly. The most widely used methods for defrosting
- To switch off the compressor, keeping a fan, allowing space heat to melt the frost.
- Through out the warm air to melt frost after the highlight reel from the cold room.
- By electric heaters resistance in thermal contact with the coil,
- Bypass capacitor and let the hot gas in the evaporator to melt the frost,
- Do not spray water on the reels, in order to melt the frost.
The most popular method is the hot gas defrost, is also comparatively less expensive, as the heat is a byproduct of the refrigeration system. The spray of water thawing is used when rapid thawing required in a production mode, where rapid return to production is essential. Electric defrosting very expensive quickly due to the high cost of electricity.
Regardless of the method, regular thawing is essential to maintain the efficiency of heat transfer in the evaporator.
Frequency of defrosting will depend on the frost construction, again depending on the materials that have been saved. Defrost on demand management, which initiates thawing according to the demand, instead of using a timer, you can save energy, where the freezing of moisture variable load.
Match the Refrigeration Capacity of the System, the real needs in the Majority of refrigeration systems oversized. Close matching of a compressor real needs automatically rises evaporator temperature and pressure, improve heat transfer efficiency and lower energy consumption at the compressor inlet. This can be achieved by disabling some machines or changing the speed of the compressor. For stationary refrigeration loads, speed can be changed by changing the pulley ratio. For fluctuating cooling load, the use of variable speed drives that may be required.
Monitor The Performance Of Refrigerating Machines
Specific power consumption (kW/TR) all major chillers should be evaluated periodically. It is often observed that the performance of similar machines is significantly different. This information can be used to maximum efficiency of the machine. Preventative maintenance can also be scheduled on the basis of this information.
The actual cooling capacity can be estimated from the water/brine flow rate and temperature difference between the evaporator or other heat exchanger. The cooling load on the unit can be evaluated with the help of air flow and the enthalpy difference between the air inlet and outlet. After measuring the dry and wet bulb temperature, enthalpy can be read from pychrometric chart. More detailed information on measurements and calculations related to bandwidth estimation chillers available in BEE Draft Code on HVAC chillers...
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Chillers