Low-cost heat pump water heater

Abstract

An improved heat pump water heater of the type having a water tank with an exterior surface and defining a water chamber, a top on the water tank with at least one opening therethrough in communication with the water chamber, and a heat pump of the type having a compressor, the compressor being in fluid communication with an annular condenser assembly via a first refrigerant conduit, the annular condenser assembly being in fluid communication with an expansion device through a second refrigerant conduit, the expansion device being in fluid communication with an evaporator through a third refrigerant conduit, the evaporator being in fluid communication with the compressor through a fourth refrigerant conduit and control means therefore, the improvement comprising disposing the annular condenser assembly through the opening in the top of the water tank and into the water chamber, the water tank opening further comprising a geometric twisted sleeve positioned to form a helical insertion pattern in the annular condenser assembly, the annular condenser assembly further comprising an elongate outer tube having a closed bottom end and an open and opposed upper end in flow communication with the first refrigerant conduit, an elongate return tube disposed within the outer tube and having an open bottom end and a closed and opposed top end in flow communication with the second refrigerant conduit, an elongate capillary tube disposed within the return tube and having an open bottom end and an open and opposed top end in flow communication with the second refrigerant conduit, and an air gap disposed between the capillary tube and the return tube.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application 60 / 664,776 filed Mar. 24, 2005, and is herein incorporated by reference. This application is also related to U.S. Pat. No. 6,233,958, issued May 22, 2001, herein incorporated by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] This invention was made with United States Government support under Contract No. DE-AC05-00OR22725 between the United States Department of Energy and U. T. Battelle, LLC. The United States Government has certain rights in this invention.FIELD OF THE INVENTION [0003] This invention is in the general field of water heaters and specifically teaches a low-cost embodiment for a heat pump water heater. BACKGROUND OF THE INVENTION [0004] U.S. Pat. No. 5,946,927 teaches a “drop-in” heat pump water heater (HPWH), and ECR International produces a HPWH based around this patent. U.S. Pat. No. 6,233,958 teaches a HPWH with ...

AI Technical Summary

Benefits of technology

[0011] The invention comprises a simple method (geometric twisted sleeve) for arranging the internal condenser by adjusting the number of coils, pitch, radius and location within the tank to affect an optimal, efficient design.

[0012] The invention comprises a linear condenser design that avoids loss of refrigerant subcooling as the refrigerant travels upward along its path out of the storage tank.

Problems solved by technology

.); however the small market that was present is drying up due to high costs based on old technologies.

HPWHs are also manufactured and sold in Asia and Australia at low volumes due to high first costs.

One problem with a desuperheater HPWH is that the house space conditioning load is usually not in sync with the water heating load.

That is, when hot water is needed, the house might not need cooling or heating, the desuperheater is therefore inactive, and water heating is provided by inefficient, backup electric resistance water heaters.

This type of HPWH is bulky, requires a water pump, and its costs tend to be high (typically $1000, or more).

A problem with all of these approaches is a market one: the costs are simply too high and as a result, the market for the HPWH is vanishing.

Most of the HPWHs mentioned require a tank that is special in some way and therefore expensive.

They are tank manufacturers, and moving into any field beyond that is simply too involved and expensive.

Other attempts at a residential HPWH have faired even worse.

Today, none of the major water heater manufacturers who produce conventional electric water heaters by the millions are interested in the current HPWH design.

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