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Avoiding Condensation On Air-exit Cover Heat Exchangers Disclosure Number: IPCOM000082945D
Original Publication Date: 2005-Feb-28
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 58K

Publishing Venue



The ever increasing heat output of computers is forcing the use of larger computer room air conditioning units. A more convenient and cost effective solution is to cool the air exiting the computer by an air-to-water heat exchanger. It is preferable from a customer point of view that below dew point cooling water be acceptable for pumping through the heat exchanger. But, if the water is below the dew point, condensation will then occur in an uncontrolled manner on the heat exchanger fins. A solution for controlling and handling the condensate, when below dew point chilled water is used, needs to be invented.

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Page 1 of 2

Avoiding Condensation On Air-exit Cover Heat Exchangers

The proposed invention limits the area of the heat exchanger over which condensation is allowed to occur. This allowed area of condensation is such that the rate of condensation is slower than the rate of evaporation of the condensate. The allowed area of condensate will be controlled by a feedback loop that controls the opening of an inlet valve. The water flowing in to the heat exchanger is throttled to achieve the allowed area of condensation.

     The figure below is an example of a rear door heat exchanger with 3 heat exchanger modules. Under each module is a drip pan. Water flow through each module is controlled so that the tubes below line A-A are below the ambient dew point. So condensation occurs on each module below line A-A. Above line A-A , the heat exchanger module is dry. The position of line A-A is chosen such that the condensation rate is lower than the rate of evaporation of the condensate dripping in the pan below the module.


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One advantage of being able to use below-dew point chilled water is that the customer is not restricted to providing chilled water above the dew point, as the present state of the art dictates. Another competitive advantage is that the invention allows the maximization of the cooling ability by being able to use colder water.