| 摘要 |
<p>Foodstuff is continuously conveyed through a tunnel in which the air is recirculated through at least two heat exchangers, connected in a compressor refrigerator system, to maintain the tunnel temp. at approx. -30 degrees C. The refrigerant used is operated at between -170 degrees C and -70 degrees C and has a vapour pressure of less than 20 atmos. in the evaporator stage. At least one of the heat exchangers employed is reversibly connected, to control frost formation.</p> |
