GB2415246A

GB2415246A - A waste water heat recovery device

Info

Publication number: GB2415246A
Application number: GB0413787A
Authority: GB
Inventors: Kim Ivor Mole
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-06-19
Filing date: 2004-06-19
Publication date: 2005-12-21
Also published as: GB0413787D0

Abstract

A waste water heat recovery device comprises a horizontal pipe through which fresh cold water flows and is disposed within a horizontal container through which waste water flows that is in heat exchange relationship with the fresh cold water so as to heat the cold water. The pipe may be made from copper and may be provided with fins and the container may be made from ABS plastics. The device may be modular and additional devices may be coupled together to increase heat recovery. If the temperature of the incoming waste water is below the temperature of the waste water in the container it is diverted via a valve to bypass the heat recovery device. The device may be installed below a bath, a shower or a kitchen unit and fitted to new build or existing houses. The heated water may be used to supply a shower, a hot water boiler or an immersion heater.

Description

241 5246

Description for Patent of:

Wastewater heat recovery system Rationale Approximately 9% of all energy produced in the UK is used to heat domestic hot water. This water is disposed of after use along with 80-90% of the energy used to heat it. Obviously considerable savings in energy usage could be achieved if this heat were recycled.

Previous attempts to recover this waste energy relied on the wastewater falling vertically down a section of copper drainpipe, and in doing so clinging to the surface in a thin film.

The device is called a Gravity Film Exchanger (GFX).

This method produces very efficient transfer of waste heat to a coldwater circuit thus pre-heating the cold water supply prior to supplying the input side of a water heating system.

However there are many problems with the implementation of this method of heat recovery.

i) The device is over two metres long and is therefore difficult to site in a domestic building.

2) The device must be mounted vertically thus demanding that the waste water supply is from a first floor device only, therefore eliminating the possibility of recycling heat from kitchen and utility appliances.

3) The device is only capable of recycling whilst wastewater is flowing through it, thereby eliminating the chance to store the energy for later use.

4) The device demands the use of highly specialized custom- made copper parts, which would make it expensive to produce, and install. This fact would create resistance to use within the marketplace, thereby limiting the benefits to the nation of large-scale energy saving.

The following is a proposal and method for achieving this saving, without the use of a GFX device.

1) Simultaneous recovery (retro fit and or new build): 2) Storage and recovery (retro fit and or new build): 3) Storage and recovery (new build): I) In this case, a heat exchange unit of small enough dimensions to be fitted under a shower or bath, is installed horizontally, with wastewater flowing through an ABS container and over a finned copper pipe containing the flowing cold water supply to either; a) Instantaneous shower water heater system, b) Cold supply to domestic hot water boiler/immersion heater or c) Cold supply of mixer system.

This example relies on the simultaneous transfer of energy from the output/waste side of the system, to the input/cold water supply as it flows into the heating/mixing system The device is modular in format thus allowing additional units to be installed as space allows, thereby facilitating increased gains and savings.

The device is capable of being retrofitted to existing systems, thereby, with the aid of grant schemes, encouraging existing households to save energy.

The device whilst less efficient than it's GFX counterpart (in this configuration) is economical to manufacture and fit, therefore producing a net gain in savings on a national scale.

The device is removable, to allow maintenance.

2) In this instance, the unit is of suitable dimensions to fit in the kicker space of standard kitchen units. In construction and installation it is similar to example 1, however, prior to the wastewater entering the exchange device it passes through a control valve, which determines the path of the water. If the temperature of the incoming water is lower than that of the water within the exchange unit, it is diverted to bypass the exchange device. If however the temperature is above that of the water in the exchange device, then the valve sets itself to allow the flow into the unit. The pre-heated cold water is then used to supply the input side of the domestic hot water heating system.

In this case, the device is capable of storing the energy in the cold water and continuing to exchange heat after the flow has ceased.

The device is modular in format thus allowing additional units to be installed as space allowed, thereby facilitating increased gains and savings.

The device is removable, to allow maintenance.

Claims

I. A non GFX heat energy from wastewater extraction device for domestic use.
2. A device as claimed in claim 1 where hot wastewater is passed through a wastewater jacket and around the cold water supply in order to pre heat said cold water supply.
3. A device as claimed in claim 1 or claim 2 where wastewater.. . which is cooler than wastewater already contained in the wastewater jacket is diverted directly to discharge.
4. A device as in claim 1,2 and 3 which can be situated horizontally.:.

under kitchen base units or under baths. . .e .. ..- ë