Micro-channel evaporator with frost detection and control

Abstract

A refrigerant vapor compression system includes an evaporator having a plurality of longitudinally extending, flattened heat exchange tubes disposed in parallel, spaced relationship. Each of the heatexchange tubes has a flattened cross-section and defining a plurality of discrete, longitudinally extending refrigerant flow passages. One or more frost detection sensor(s) is / are installed in operative association with the evaporator for detecting a presence of frost / ice formation on at one of the flattened heat exchange tubes and associated heat transfer fins. A defrost system is provided and operatively associated with the evaporator heat exchanger. A controller, operatively coupled to the frost detection sensor(s) and to the defrost system, selectively activates the defrost system to initiate a defrost cycle of the evaporator in response to the signal indicative of the presence of frost formation on the flattened heat exchange tubes and heat transfer fins.

Description

technical field [0001] The present invention relates generally to evaporative heat exchangers, and more particularly to providing improved control of frost buildup on the exterior surfaces of evaporative heat exchangers having a plurality of parallel, flat heat exchange tubes. Background technique [0002] Air conditioners and heat pumps employing refrigerant vapor compression cycles are commonly used to cool, or cool / heat, the air supplied to climate-controlled comfort zones within residences, office buildings, hospitals, schools, restaurants, or other facilities. Refrigerant vapor compression systems are also commonly used to cool air, or other secondary media such as water or glycol solutions to cool display cases, bottles in supermarkets, convenience stores, grocery stores, cafeterias, restaurants, and other food service establishments Provides a refrigerated environment for food and beverages in refrigerators or other similar equipment. [0003] Traditionally, these re...

AI Technical Summary

Problems solved by technology

Since water expands when it freezes, the repeated freezing and thawing of accumulated condensed water, especially in the confined space between the heat transfer fins and the flat heat exchange tubes (for example, in the fins in the area that contacts the flat tubes) can damage the heat exchanger by deforming or cracking the tubes and causing the fins to separate from the tubes

Additionally, during subsequent defrost cycles, more ice may accumulate on the outer surfaces of the heat transfer tubes and heat transfer fins of the evaporative heat exchanger, and may even completely block the airflow passages, forcing the evaporator to operate at a specific range (in terms of suction pressure) and jeopardize the reliability of the refrigerant system or cause an unfavorable shutdown, both of which are clearly highly undesirable events

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