US2968934A

US2968934A - Heat pump systems

Info

Publication number: US2968934A
Application number: US718173A
Authority: US
Inventors: Komedera Mieczyslaw
Original assignee: Heat Pump & Refrigeration Ltd
Current assignee: Heat Pump & Refrigeration Ltd
Priority date: 1957-03-05
Filing date: 1958-02-28
Publication date: 1961-01-24
Anticipated expiration: 1978-01-24
Also published as: BE565337A; GB821079A; DE1102187B

Description

Jan. 24, 1961 M. KOMEDERA HEAT PUMP SYSTEMS 2 Sheets-Sheet 1 Filed Feb. 28, 1958 A m mm N R E 0 vM W w +A K YZ W 1 C M M w Jan. 24, 1961 Filed Feb. 28, 1958 2 Sheets-Sheet 2 23 A COMMON TART MOTOR TERM/NAILS 3] l8 2? l E amaz E1eaisz lasz Eil NEUTRAL;

EARTH SUPPLY PHASE /A/VN7D,Q Mieczyslaw KOMEDERA ATTORNEYS Unite States atnt C HEAT PUMP SYSTEMS Mieczyslaw Komedera, High Wycombe, England, as-

signor to Heat Pump 8: Refrigeration Limited, London, England, a British company Filed Feb. 28, 1958, Ser. No. 718,173

Claims priority, application Great Britain Mar. 5, 1957 3 Claims. (Cl. 62-197) The present invention relates to heat pump systems and in particular to a compression type heat pump system employed for heating water.

In ordinary house construction it is usual for the hot water storage tank to be located at some distance from the larder or from a position at which it would be convenient to locate a refrigerator. In a heat pump system which supplies heat to a domestic hot water system it is not convenient to locate the compressor and condenser of the system near to the evaporator, particularly if the evaporator is used to extract heat from the larder of the house. In many cases the larder is quite a small room and it is undesirable to have space taken up in it by the motor and compressor unit of a heat pump system.

It is an object of the present invention to provide an improved heat pump system for domestic water heating combined with room cooling and/or refrigeration, taking the above factors into account.

It is a further object of the invention to provide an efiicient and compact heater unit comprising a motordriven compressor and a condenser in heat exchange relation with the water heating system.

According to one aspect of the present invention a heat pump system is characterised by a condenser comprising an inner tube through which the compressed refrigerant issuing from the compressor passes downwardly and an outer tube through which the water or other liquid to be heated passes upwardly in counter-current direction to the descending refrigerant.

The condenser is preferably in the form of a coil of large diameter having a vertical axis and is arranged so that it is possible for the water passing through the condenser to take up heat not only through the inner tube from the heated refrigerant issuing from the compressor but also to take up heat through the outer tube from coolant liquid which receives heat as a result of the heat generated in the motor compressor unit. For this purpose the motor compressor unit of the sealed type is submerged in an externally lagged closed container tilled with coolant liquid and the condenser coil is either submerged in the liquid around the motor compressor unit or is soldered around the outside of the container, which is, in that case, made of a heat conductive material. It will be observed that the water receives heat both at the inner surface and at least a part of the outer surface of the annular passage through which it passes, so that efiicient use is made of the materials employed in the construction of the condenser unit.

According to another aspect of the invention a heat pump system is characterised by a main evaporator and a subsidiary evaporator adapted to receive refrigerant from the condenser of the system, the subsidiary evaporator being located within an enclosed insulated cabinet, the subsidiary evaporator being located in a by-pass line from the main line connecting the condenser to the main evaporator, means being provided to control the flow of refrigerant through the subsidiary evaporator in response to the temperature in the insulated cabinet. Preferably the flow path through the subsidiary evaporator has a greater resistance to flow than the main path and the main path is adapted to be shut off by means of a valve controlled by a thermostat in the insulated cabinet. v One construction of apparatus made in accordance with the invention is shown in the accompanying drawings, wherein:

Figure 1 is a partly diagrammatic section of a heat pump system assembled into a domestic sink unit, and Figure 2 is a diagram of the electrical connections between the various elements. In the construction shown .the motor compressor unit and condenser unit are mounted under the sink of a sink unit and an insulated cabinet for refrigerator purposes is located beside it under the draining board of the sink unit. The motor compressor unit and condenser unit may, however, be mounted in the base of a refrigerated cabinet in the manner conventional for domestic refrigerators.

In the construction shown there is provided a heat or insulated container 1 which is filled with oil or other heat conducting (and electrically-insulating) liquid, in which is submerged a sealed-type motor compressor unit 2 of known design. The refrigerant condenser is in the form of a coil 3 arranged in the container 1 around the motor compressor unit with the compressed refrigerant entering the top end of the coil 3 by Way of the pipe 4 and being drawn away from the bottom of the coil in a manner that will be described later. The tubular condenser coil 3 passes co-axially through an outer tubular water coil 5 through which water circulates, passing upwardly, preferably under the influence of a thermo-syphon. The two ends of the water tube are taken out through the side or top of the casing and led to a hot water tank (not shown) in the conventional manner. The water drawn through the coil 5 in contact with the condenser coil 3 may come directly from the hot water tank or from a closed coil submerged in the tank. In the latter case the coil may be filled with some other liquid than water, although the thermal characteristics of water make it very suitable for this purpose.

In operation all the heat generated in the sealed motor compressor unit by reason of friction losses and work done in the compressor and the heat generated in the motor itself is taken up by the oil in the container 1. Since, however, the container 1 is insulated against heat loss, the bulk of this heat is taken up from the oil by water passing through the coil 5.

The arrangement of the refrigerant condenser coil 3 and the water heating coil 5 is such that the de-superheating of the refrigerant takes place at the top of the condenser coil and the liquid condensate accumulates at the bottom. The arrangement of the condenser is such that it is always self-draining, thus preventing any refrigerant or oil from being trapped in the condenser.

The liquid line for the refrigerant issuing from the bottom end of the condenser coil is led upwardly through a dryer 7 to a main restrictor 8. The refrigerant issuing from the restrictor 8 may reach the main evaporator 9, which is preferably situated in the larder of the house, through two different paths. In the first (and main) path it is passed through a lead 10 (giving a very little pressure drop) and a solenoid shut-off valve 11 to the main evaporator 9. In the second or by-pass path it passes through a second restrictor 12 and a liquid accumulator 14 to a subsidiary evaporator 15 located in an insulated refrigeration cabinet 16 of the apparatus. After passing through the subsidiary evaporator 15 the refrigerant by-pass line 17 re-joins the main line 10 above the solenoid shut-off valve 11. The solenoid shut-off valve 11 is operated by means of a thermostat 18 located in the refrigerated cabinet, so that the shut-off valve is closed when the temperature in the cabinet reaches a predetermined maximum and this by-passes the refrigerant through the subsidiary evaporator 15 before it reaches the main evaporator 9. When the valve 11 is open the amount ofrefrigerant passing through the subsidiary evaporator 15 in the refrigerated cabinet is quitesmall, because of the restrictor 12. The terminal portion 10 of the main refrigerant line, from the point where it has been rejoined by the by-pass refrigerant line 17, is preferably a semi-flexible or flexible pipe of low resistance to flow and well insulated to prevent condensation on it.

The main evaporator 9 is of large size and preferably of extended surface. A small fan 19 may be located close by it to induce a flow of air over the evaporator coil 9. The return line 20 from the main evaporator to the motor compressor unit 2 may also be a semi-flexible 'or flexible tube. Both the tubes 10' and 20 which connect the apparatus with the evaporator should be well insulated to prevent condensation on them and the length of these tubes should not exceed the length of the evaporator coil 9 and should offer little resistance to the flow pfrefrigerant, through them.

"The motor 21 driving the fan 19 which induces the flow of air over the main evaporator, may be controlled :by a thermostat 22 located in theinlet of the water heating coil 5, so that the fan 19 is brought into operation when the temperature of the water flowing into the coil drops below a certain predetermined temperature and conversely if the water temperature rises, the heat intake is reduced by switching off the fan.

If no, or little hot water is drawn off from the hot water system, as for instance during week-ends, there is a tendency for the temperature of 'the water in the coil to rise even further, which would cause the condenser pressure to rise to an abnormal level and the motor to be over-heated. To overcome this difficulty, a second thermostat 23 is fitted in the ou tiet of the water heating coil and this controls a heat-leak solenoid valve 24 which releases hot water to waste thus admitting cold water into the coil. The thermostat 23 will react to the cold water entering the coil to close the heatjle'ak solenoid valve 24. The valve will again open when the water in the coil is heated to 140 F. and more cold water will be drawn into the coil. This ensures that only surplus hot water is released from the system and the efficiency of the system is maintained.

7 In order to provide hot gas defrosting of the evaporator a connection may be madeffrom" the outlet of the compressor through a valve 30 (not shown in Figure 1) which may be controlled either manualy or by a, thermostat 3ltas shown in Figure 2, tothe main line it) beyond the restrictor If a solenoid-operated valve is employed in the hot gas defrosting line, then this may be controlled by ineans of a thermostat arranged at the outlet end of the main evaporator 91, the thermostat being effective to 'open'the valve when the temperature of the refrigerant issuing from the main evaporator falls below a predetermined temperature.

In a modified construction the size of the container 1 is reduced so as to be only sufliciently large to hold 'an'adequate volume of coolant for the motor compressor unit. The combined refrigerant condenser coil and water heating coil' are then Wound around the outside of the container and soldered thereto, so that the water heating coil is in heat exchange relation with the container wall and can take upheat from it.

This constructioninvolves a small loss of heating efficiency. On the other hand it does permit the apparatus to be more compact and also obviates bringing the water heating coil in through the side of the condenser.

I claim: 7

1. Ida heat pump system in combination a motor agrees compressor unit, a refrigerant condenser means connected to the outlet of said motor compressor unit, a water conducting means arranged to take up heat from refrigerant passing through said refrigerant condenser means, a main evaporator means connected with the inlet of the motor compressor, a main refrigerant line leading from said refrigerant condenser means to said main evaporator means, an insulated cabinet, a subsidiary evaporator means arranged within said insulated cabinet, at bypass line connecting both ends of said subsidiary evaporator means with said main line at spaced points, a single shut-off valve in said main line between said spaced points, and a control circuit for controlling said shutoff valve, comprising a single thermostat which is positioned within said insulated cabinet and is exposed to the interior thereof and is responsive to the temperature therein and controlling said shut-off valve to close the same when the temperature in the insulated cabinet exceeds a predetermined maximum, the said by-passline having fiow resistance means therein and the said main line between said spaced points being obstructed only when said valve is closed. I

'2. In a'heat pump system the combination of a sealed unitary casing having a motor compressor unit therein, aheat-insulatedcasing surrounding said motor-compressor casing, said heat-insulated casing being filled with an electrically insulating coolant liquid to receive heat generated in said motor compressor, a condenser coil connected with said motor compressor unit and arranged about said unitary casing, said condenser coil lying within an outer coil of greater diameter so as to define an annutar passage for water between the inner coil and the outer coil, means for passing water through said annular' passage countercurrent to the flow of refrigerant through said condenser coil and said water heating coil being arranged in heat exchange relation with said coolant liuid, whereby heat is transferred to the water through the walls of the inner coiland of the outer coil simuland water heating coil structure being arranged around the motor compressor casing within said heat insulated casing, said condenser coil being connected to said motor compressor unit in such manner that refrigerant flows downwardly through the condenser coil and means for "passingf'waterupwardly through said annular passage in countercurrent relation to the refrigerant, whereby the water receives heat simultaneously by heat exchange from the refrigerant through the wall of said condenser coil and from the coolant liquid through the wall of said water heating coil.

References Cited in the file of this patent UNITED STATES PATENTS 1,924,525 Taylor Aug. 29, 1933 2,108,898 Lyons Feb. 22, 1938 2,150,993 Smith Mar. 21, 1939 2,687,020 Staebler Aug. 24, 1954 2,696,085 Ruff Dec. 7, 1954 2,821,844 Olson Feb. 4, 1958