GB2444275A

GB2444275A - Device to store and deliver hot water

Info

Publication number: GB2444275A
Application number: GB0624014A
Authority: GB
Inventors: Matthew Bruce Shearn
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-12-01
Filing date: 2006-12-01
Publication date: 2008-06-04
Also published as: GB0624014D0

Abstract

The device 1 for storing and delivering domestic hot water, to a kitchen sink for example, contains water heated by waste heat from a compressor 15. The compressor is part of another appliance 16 nearby such as a refrigerator, freezer or air conditioning unit. The water is kept hot by recirculation through a heat exchanger 2 that is an integral part of the compressor. The storage device may have a variable volume 11 so that when a quantity of hot water is used it is not diluted by cold water entering the device. Cold water is heated before entering the storage device by passing it through the heat exchanger. When all the stored hot water is used up a smooth switch over to another source of hot water may be achieved.

Description

S 2444275 A device to store and deliver hot water that receives heat

from a compressor Tbis invention relates to a hot water storage device that holds a quantity of water, whereby the water is heated by the rejected heat from a compressor fitted to an appliance, such as a fridge, freezer, fridge-freezer combination, air conditioning system or heat pump. The storage device is a separate unit that can be fitted in a convenient location in proximity to the appliance. Cold water is warmed by the heat produced from the compressor. This heat is generated by the electrical and mechanical work done internally by the compressor, and the heat from the compression of the refrigerant that the compressor cireulates around the appliance.

The hot water is stored until needed, for example to fill a kitchen sink for washing, to supply a washing machine or any other use. For example the water that has been warmed by the heat from the compressor could contribute to warming up a larger volume of water used to supply the whole house with hot water.

An energy saving is achieved by using the heat that is normally released to the sulToundings to heat the water instead. Also hot water is available from the tap sooner so less water is wasted zumaing the tap. With additional plumbing the hot water can be supplied to a larger storage tank to assist in warming up a greater quantity of water.

Separate devices may be connected to a combination of appliances available in the same property to provide more hot water to a larger storage tank.

A specific embodiment of the invention is described where the storage device (1) is a slim rectangular shape that can fit under the kitchen units (21) at floor level, and is connected to a fudge-freezer appliance (16) that is close by with pipes (4), such as shown in Figure 1.

The plinth that normally covers the feet of the kitchen units has been removed for visability.

With reference to the schematic shown in Figure 2, the storage device (1) captures heat by means of the coiled pipe (2) that is fitted around the outside of the compressor (15). and acts as a heat exchanger. The other components of the refrigeration cycle, namely the condenser, expansion valve and evaporator have not been shown separately (10), but are contained within the appliance. The pipes (7) that connect the compressor to the other components of the appliance are not interfered with, and the appliance (16) which is indicated by the chained boundary line, is not altered substantially apart from the changes to the compressor. The therniodynainic cycle of the appliance that the compressor is fitted to cperates as normal.

Cold water from the supply (3) is prevented from entering the storage device directly by a non-return valve (17). Instead the water passes through the coiled pipe (2) by the connecting pipes (4), and is then stored in the device. The connecting pipes can be cot to the required length for the distance separating the device and appliance. Previously warmed water (5) held in the storage device may also pass through the coiled pipe to keep it warm or warm it up further. Once warmed, the water is kept as hot as possible by insulation (6) surrounding the storage device, the pipes connecting it to the compressor and the compressor itself: The removal of heat from around the compressor may be controlled by the inlet 3-way valve (8) that regulates the entry of cold water from the supply (3), or a pump (9) that circulates water from the device around the coil. The amount of heat captured from the compressor must not be so great that there is a danger that the refrigerant vapour will condense inside the compressor and cause hydraulic damage. The flow of the water around the coil can be controlled by a microprocessor (19) such that the thermodynamic efficiency of the appliance that the compressor is fitted to is optimised. By this it is meant that the thermodynamic conditions used to calculate the cycle efficiency of a vapour-compression cycle (more specifically the Carnot cycle) are improved.

Water that has initially been warmed is stored inside the device (5). This volume is variable and can be altered by an expansion device (11). Typically the expansion device may be a thick rubber balloon with a preset internal pressure or bellows whose movement is controlled by internal air or spring forces. Similar expansion devices are already available for a variety of uses, such as domestic central heating systems or industrial processes where compensation must be made for the temperature of fluids in the system.

The expansion device is integral to the hot water storage device herein described, so volume (5) may vary from say 5 to 25 litres. The purpose of the expansion device is to allow all of the water held within the storage device to be at a usable temperature, even if the volume of hot water has not reached the maximum capacity. It takes several hours for the water to pass through the heating coil (2). be heated to a useful temperature and fill the storage device completely. Without the expansion device the maximum capacity of water would have to be warmed up over this same period of time, but none could be used until it was sufficiently warmed.

Other methods of varying the volume for the hot water storage may be devised where an insulated dividing component separates the warm water on one side from cold water on the other side. As the water is warmed it displaces the cold water by free or forced movement of the dividing component within the device.

Hot water is drawn from the device by opening the hot tap, and with the outlet three-way valve (12) open in position BC, the expansion device (11) forces water out. The inlet 3-way valve (8) is kept closed to avoid mixing cold water with the stored hot water. Once the demand for hot water is satisfied (hot tap closed) cold water is allowed to enter the device via the inlet three-way valve (8) set in position XZ, passing through the coil (2). The device is replenished with water that is heated via the compressor waste heat.

If all of the hot water is drawn from the device a pressure sensor (13) detects that the delivery pressure has fallen below a set level and the inlet three-way valve (8) is opened in position YZ (position XZ is kept closed). Hot water is then delivered from an alternative hot water supply, which could be the main hot water tank fitted in a house or a combi' boiler intended to supply direct hot water. This water is not initially hot since it has been standing in the hot supply pipe (14) for a long time. It typically takes a couple of litres of cold water to flow through the pipe work for the hot supply to reach the device. When the temperature of the water entering the device matches the temperature of the stored water leaving the device the outlet three-way valve (12) is switched over to supply hot water directly from the alternative supply (valve position AC open and BC closed). In this way there is a seamless switchover in delivered hot water temperature when the device is depleted, rather than cold water being delivered whilst the supply pipe (14) is purged of standing water.

A temperature sensor (18) monitors the water temperature from the coil (2) to control the inlet valve flow rate, or the arrival of hot water from the alternative supply. The inlet valve may be operated by a duty cycle controlled solenoid to achieve fine flow control of water, typically 50 cc/mm (3 litres per hour), when heat is transferred from the compressor, but high flow rates for a short time when standing water from the hot supply is purged from the pipe (14). The high flow rate of cold water around the compressor for a short time does not present a risk of refrigerant condensation and hydraulic damage.

The inlet and outlet three-way valves can be integrated into the storage device so only cold and hot inlet and outlet pipe connections are needed. Furthermore if the device is not connected to a household hot water supply or combi boiler (maybe due to its location, the preference of the owner or a system is not present), then a small electric immersion heater element (20) can be fitted to the device to heat an initial volume (5 litres) of water rapidly.

This avoids a long delay after all the hot water has been used up before a limited amount of hot water is available again. The device is supplied with mains electricity (21).

Claims

Claims 1. A device to store and deliver water that has been heated by

the compressor of an appliance such as a refrigerator, freezer or air conditioning unit.
2. A device that is separate from an appliance such as a refrigerator, freezer or air conditioning unit, and heat is transferred to it by pipes that do not carry the refrigerant that is used in the vapour-compression cycle of the appliance.
3. A device according to claims 1 or 2 where the compressor is a part of an appliance that operates on a vapour-compression cycle, which is not altered in any way apart from the means to capture the heat from the compressor.
4. A device according to claims 1 or 2 where water is heated directly by passing it around the inside or outside of a compressor.
5. A device which improves the thermodynamic efficiency of a domestic refrigeration appliance that operates on the vapour-compression cycle by utilising a variable heat sink that accepts heat from the compressor and uses the heat to warm water for domestic purposes.
6. A device according to claims 1, 2 or 5 where the water is stored at a temperature that is immediately useful for domestic purposes, and the volume of stored water increases with time by means of an expansion device (11) or an exchange of stored cold water for stored hot water within the device.
7. A device according to claims 1, 2 or 5 whereby the switch over to another supply of hot water is achieved when the storage device is empty of hot water without the delivery of hot water being interrupted.
8. A device to store and deliver hot water that fits under the kitchen units so useful storage space inside the units is not lost.
9. A device according to claims 1, 2 or 5 where the hot water is supplied to a larger hqt water storage device used in the same property.