Frost sensor for use in defrost controls for refrigeration
US6467282B1 · kind B1 · utility
Inventors
Key dates
| Filing date | Sep 18, 2001 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Sep 18, 2021 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF25B2700/11
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method for measuring the total thermal resistance to heat flow from the air to the evaporative cooler fins of a refrigeration system. The apparatus is a frost sensor that measures the reduction in heat flow due to the added thermal resistance of ice (reduced conduction) as well as the reduction in heat flow due to the blockage of airflow (reduced convection) from excessive ice formation. The sensor triggers a defrost cycle when needed, instead of on a timed interval. The invention is also a method for control of frost in a system that transfers heat from air to a refrigerant along a thermal path. The method involves measuring the thermal conductivity of the thermal path from the air to the refrigerant, recognizing a reduction in thermal conductivity due to the thermal insulation effect of the frost and due to the loss of airflow from excessive ice formation; and controlling the defrosting of the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.