Adequate cleaning of a milk cooling tank (and milking equipment) should normally be done with a hot detergent solution. At the farm, it is not always easy to have hot water and having it results in energy expenditure whose cost is increasing. However, the heat extracted from the milk is discharged in vain into the air by the condenser of the refrigeration unit.
Some might think that if one places a heat exchanger on the pipe from the compressor to the condenser and in which circulates the hot vapors of the refrigerant, it is possible to partially recover the heat. The current collectors are made of calories exchanger a refrigerant heat - more or less complex water. The simplest type is a coil immersed in a container of water in which circulates the hot refrigerant. The vapors of the latter reach at least 80 ° C. Upon arrival of the milk of the first milking in the direct expansion tank, the refrigeration unit is turned on. The condensation temperature of the refrigerant becomes rapidly higher than that of the water contained in the exchanger.
After a certain operating time (20-30 minutes) the two temperatures are equalized and then reversed. Indeed, the recovery system water is heated and the condensation temperature decreased along a curve approximately follows that of the milk temperature. Heat recovery is then much weaker and the water temperature stabilizes quickly. Ultimately, the recovery is about 30% of the total amount of heat is produced, which represents approximately 45% of the milk. In subsequent milkings the amount of recovered heat is even lower because the condensation temperature is lower because the hot ugly mixture temperature cooled milk + is lower than the first draft.
Thus, CHARRIAU does not recommend to use heat recovery system for milk cooling tanks. It is not efficient enough and also increase "bad luck" risks for the gas circuit of the refrigeration unit of the milk cooler.
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This technology applies the principle of thermodynamics, using air as an energy source and ensures 75% of free energy.