Grey water heat recovery system

Abstract

A grey water to clean water heat exchanger and methods of use. A heat exchanger having a copper coil carrying clean water inside a grey water discharge pipe is described. The heat exchanger can use counterflow geometry. The heat exchanger has a controller that directs grey water through a bypass pipe whenever the grey water has too low a temperature to provide useful thermal energy. When the grey water is hot enough, the controller directs it through the heat exchanger to heat the clean water. A filter is provided to eliminate fouling of the interior of the heat exchanger. The controller provides an indication when the filter needs to be cleaned or replaced.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to and the benefit of co-pending U.S. provisional patent application Ser. No. 61 / 266,275, filed Dec. 3, 2009, which application is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The invention relates to heat recovery systems in general and particularly to a system that recovers heat from waste water.BACKGROUND OF THE INVENTION[0003]There is a growing need for a simple system that recovers energy from hot commercial wastewater. The equivalent of 235 billion kWh worth of hot wastewater is discarded annually in the United States according to the U.S. Department of Energy. A significant amount of the energy from this wasted hot water could be recovered. Desirable features of such a system would include easy installation, minimal impact on existing plumbing and low maintenance. Over time a wastewater recovery system will be able to pay for itself through savings earned from energy ...

AI Technical Summary

Benefits of technology

"The invention is a grey water to clean water heat exchanger that uses a discharge pipe and a helical coil to transfer heat from grey water to clean water. The system includes a filter to remove material from the grey water, a bypass valve to control the flow of grey water, and a controller to activate or deactivate the bypass valve. The system can recover thermal energy from the grey water and use it to heat the clean water. The technical effects of the invention include efficient energy recovery and improved clean water quality."

Problems solved by technology

Heat energy is also lost in other waste water systems used in residential and commercial environments.

This loss of energy is especially prevalent in businesses or commercial locations such as residence halls, barracks, gym locker rooms and laundromats where large amounts of hot water are being used continuously throughout the day.

One area where energy is wasted on a regular basis is the hot water being sent down drain after showering, washing hands, and doing the laundry.

None of these devices are rated to capture more than fifty percent of the energy within the grey water going down the drain or to handle the capacity of more than two full bathrooms.

With this design the water travels extremely fast through the system due to the fact it travels straight down the pipe with no obstructions, this would require the pipe to be extremely long to recover a beneficial amount of heat.

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