GB1533651A - Dehumidifying methods and means - Google Patents

Abstract

1533651 Drying using a heat pump EBAC Ltd 6 Feb 1976 [7 Nov 1974 (2)] 48262/74 and 48263/74 Heading F4G In a method of drying, e.g. timber T, using a refrigeration or heat pump arrangement incorporating a condenser stage in which a refrigerant fluid is condensed at not less than 60‹ C., whereby the relative humidity of an air flow used for drying is reduced, the ratio of the heat rejection rate (Kilocalories/sec.) obtained in the stage, to the rejection capacity (Kilocalories/sec./ OC LMTD) of the stage, is not more than 14 :1 whereby to maintain an LMTD (logarithmic mean temperature difference) in the stage at less than 14‹C., preferably not more than 11‹C. The method makes possible operation at higher temperatures with a given refrigerant fluid. LMTD is defined with respect to the temperature differences between the refrigerant fluid and the air at the air inlet and air outlet to the condenser. In one embodiment, Fig. 1, (not shown), the evaporator and the condenser of the heat pump arrangement are in a common casing and the air is circulated through both. Some of the air may bypass the evaporator. In another embodiment, Fig. 3 (not shown), ambient air is used to heat the refrigerant fluid in the evaporator, which is outside the casing.