Inventors:
Patricia Duenes - Irvine CA
Richard L. Kenyon - Irvine CA
John N. Scapes - Schamburg IL
Eugene H. Schild - Des Plaines IL
Arthur P. Strong - Prospect Heights IL
Assignee:
Parker Hannifin Corporation - Cleveland OH
International Classification:
F25D 2102
Abstract:
Apparatus for detecting frost buildup on an evaporator (34) of a refrigeration system (10) includes an air velocity sensor (42) in the air flow path. The sensor is connected to an analog to digital converter (46) which delivers binary signals representative of air velocity to a microcomputer (50) which includes a processor and a memory. Microcomputer (50) is programmed to prompt an operator through a screen (56) at a user station (52) to input an air flow reduction factor at a keyboard (54). The microcomputer uses the air flow reduction factor and the velocity sensed when the evaporator is fully defrosted to calculate a defrost initiation value. When the air velocity sensed at the sensor is no longer greater than the initiation value the microcomputer generates a defrost initiation signal. The microcomputer also includes a timer clock and periodically prints at a printer (58) the time and the velocity sensed.