Thermal energy storage device and method

Abstract

A thermal energy storage unit is provided for a conventional an air conditioning system having a compressor, a condensing unit, an expansion unit and an evaporator, all operative interconnected. The thermal energy storage unit is located exterior to a structure to be cooled and is connected solely to refrigerant lines running to and from the compressor without altering the existing expansion unit and evaporator unit located within the structure. The air conditioning system is operated through at least two distinct phases of operation, one phase of operation including the running of the compressor to supply refrigerant to the expansion unit and the evaporator unit to cool the indoor space inside the structure and another distinct phase of operation being the operation of the thermal energy storage unit to exactly simulate the running of the compressor without powering the compressor.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an energy storage device that can easily be added to an existing Freon compression air-conditioning system commonly used in residential and small commercial applications. The method of the invention allows the addition of a single thermal energy storage unit which will replicate the operation of a conventional condensing unit while using only energy that was previously stored in the existing system without any change or alteration of existing equipment. [0003] 2. Description of the Prior Art [0004] As a result of the growing popularity of air-conditioning, electrical demands have increased drastically in certain areas. A particular problem exists because of the common demand for air-conditioning power during the hottest portion of the day. Such demands tax electrical generation plants and the electrical distribution systems presently in place. In order to counter this common demand, ...

AI Technical Summary

Benefits of technology

[0026] The present invention provides a novel energy storage device or system which can easily be added by retrofit to an existing Freon compression air-conditioning system of the type commonly used in residential and small commercial structures. The system of the invention is also easily incorporated into new construction with relatively little additional expense. The method and device of the invention allow the addition of a single “package” to a new or existing air conditioning system that totally simulates the operation of the conventional condensing unit. The system of the invention uses only energy that was previously stored by the system and does not require any change or alteration of existing equipment inside the structure. The add-on package of the invention creates a new system that stores energy in a first time period, utilizes this stored energy during a second time period to cool the structure, and possesses the capacity to be able to cool the structure in a third time period without utilizing stored energy.

Problems solved by technology

A particular problem exists because of the common demand for air-conditioning power during the hottest portion of the day.

Thermal storage devices of this last type have had some success in new construction, but have had very limited use in existing structures because of the initial expense and inconvenience of installation.

One limitation on the use of existing technology has been the requirement that the existing equipment be greatly modified, including modification of the evaporative coil or related equipment already located within the interior of the structure being cooled.

Another principal limitation on the use of the third type of thermal energy storage system described above relates to the various difficulties that are encountered in pumping liquid Freon which is condensed in the ice tank.

A basic problem exists with respect to all of the existing methods, however, because cooling of the structure with a conventional condensing unit requires an expansion device to hold back pressure on the cooling coil to enable the hot high pressure Freon leaving the compressor to condense to a liquid at a temperature that is close to ambient.

This pressure differential is easily provided by the compressor but has not been achieved by the liquid pump required in the second time period because of the characteristic properties of the liquid Freon present in the ice tank summarized above.

This is costly, inconvenient, and impractical in most cases.

This arrangement works adequately in the time period three, but requires an additional line to be run into the structure for time period two operation when the pump is running because the pump can't overcome the high pressure which is present.

Again this new line is costly, inconvenient, and impractical in most cases.

This patent does contain a very brief comment that the pump could be discharged upstream of the expansion device, but it does not present any plan for getting around the pumping problems.

This method is costly, inconvenient, impractical but does demonstrate the problems involved in pumping the liquid refrigerant.

This type of expansion device is rarely used in residential and small commercial systems because of the attendant cost.

The problem of transferring refrigerant to the suction of the pump to raise the net positive suction pressure of the liquid in an effort to reduce cavitation is not addressed.

However, the system would be costly and have limited pump life.

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