EP0013669A1

EP0013669A1 - Heating device

Info

Publication number: EP0013669A1
Application number: EP79900388A
Authority: EP
Inventors: Kurt Evald Karlsson; Peter Emanuel ASTRÖM
Original assignee: TEKNOTERM SYSTEMS AB
Current assignee: TEKNOTERM SYSTEMS AB
Priority date: 1978-04-03
Filing date: 1979-11-05
Publication date: 1980-08-06
Also published as: GB2036279A; NO791062L; DK454379A; JPS55500258A; SE432661B; SE7907539L; WO1979000874A1; SE7803706L

Abstract

Dispositif de chauffage concu pour une habitation et comprenant une pompe thermique. L'evaporateur (1) de la pompe thermique est place dans un recouvrement (10) dans lequel de l'air exterieur, de l'air perdu de ventilation et/ou de l'air chauffe par tout autre moyen s'ecoule et touche directement l'evaporateur pour lui transferer sa chaleur. Le condensateur de la pompe thermique consiste en un ou plusieurs elements (3a, 3b), qui sont en contact direct avec l'air des pieces a chauffer.Heating device designed for a home and comprising a heat pump. The evaporator (1) of the heat pump is placed in a cover (10) in which outside air, lost ventilation air and / or air heated by any other means flows and touches directly the evaporator to transfer its heat to it. The condenser of the heat pump consists of one or more elements (3a, 3b), which are in direct contact with the air in the rooms to be heated.

Description

HEATING DEVICE

The present invention relates to a heating device, consisting of a heat pump to heat the rooms of for example a house and an industrial building, different forms of ambient heat, for example solar heat, soil heat, exterior air heat, waste water heat, waste air heat and attic air heat being utilized. The heat is absorbed in the evaporator of the heat pump and is utilized to heat the rooms of the building by means of the condenser of the heat pump.

It is known in the art to use a heat pump to meet the heat requirement of various types of buildings, for example small houses. In these well-known applications the evaporator customarily is placed in the basement of the house or outside the house and is arranged to interact with the exterior air, from which heat is absorbed, and the condenser of the heat pump is by means of a heat exchanger connected to the loop of a water type or air type radiator system in the house. One of the drawbacks of such devices is that a portion of the heat generated by the heat pump is lost in the heat exchanger.

Heat pumps designed to heat the rooms of a building usually are compact units, which are delivered to be installed either indoors or outdoors. The evaporator portion and the condenser portion usually are installed in one and the same box. Intake air or water, which has absorbed ambient heat, or the like is pumped through the evaporator portion of the unit and gives off its heat to the evaporator and furthermore air and water or the like are pumped through the condenser portion of the unit and absorbs condenser heat to be distributed to the radiators in the various rooms of the building. Unfortunately, it is quite complicated and expensive to install the heat pump system, which consists of several portions as well as ducts and piping, required to attain passage and circulation of air and/or a liquid heat carrier, besides the automation equipment required to control ventilators, pumps, adjustable valves etc. The efficiency of the system is also low, particularly in the winter, when a large pump height is used in order to impart to the heat carrier in the radiators of a customary type a working temperature, for example 50-60°C.

In the Swedish patent 127 298 a method is described, in which a heat pump is used to heat a building unit without resorting to any intermediate heat exchange. In this case however, the evaporator of the heat pump is placed in a space, in which animals are confined. Thus, the heat, which radiates from the animals, is used to heat the building unit. This system is simple and efficient, provided a space, for example a cowhouse accomodating .a number of animals, is available. However, for example in a city dwelling area cowhouses are not always available, providing a supply of a quite large heat quantity, but the heat required to be supplied to the evaporator of the heat pump system must be absorbed from the exterior air or be supplied to the evaporator in some other way.

The purpose of the present invention is to build a simple heat device, consisting of a heat pump, a system substantially without any movable parts such as pumps, ventilators, valves etc and without special arrangements for heat exchange, neither between ambient heat sources and the evaporator of the heat pump or between the condenser of the heat pump and the rooms of the building, in short a heating device, which is simple and economical to install and use. Another purpose of the present invention is the utilization of the ambient self-ventilation to efficiently absorb ambient heat in the evaporator of the system and thereby improving the efficiency as far as the recovery of heat in for example waste air and attic air is concerned. A third purpose of the present invention is to attain better economy as to the heat requirement for the whole year, in mild as well as cold weather. A fourth purpose of the present invention is to eliminate or reduce frost and ice formation on the evaporator of the system and lowered efficiency caused thereby without resorting to a defrosting device.

According to the present invention it has been found, quite unexpectedly, that the above-mentioned purposes may be attained in a most satisfactory manner in case the basic idea according to the Swedish patent 127 298, which is characterized by a single circulation path in the whole heat pump system, is modified thereby making it possible to utilize such minor ambient heat sources as the heat of exterior air, waste air, attic air, soil and the sun. When the efficiency and the heat economy of various known and marketed heat pump systems designed to heat houses were evaluated as references and the same parameters of the system according to the present invention were evaluated, it was found that on an average the system according to the invention, as far as the efficiency goes, was quite comparable with known systems and also the new system is quite less expensive to purchase, install and maintain.

The characterizing feature of the heating device of the present invention is that the evaporator of the heating pump is placed outside the building and is surrounded by a covering protecting from wind and weather. Exterior air, wasted ventilation air and/or air heated in any other way flows into this covering and passes by the evaporator. The passage by the evaporator is caused by the fact that precisely the amount of air, which at any given time surrounds the evaporator, directly and without any heat transmittance medium whatsoever gives off its heat to the evaporator, is thereby cooled and moves downwards and finally out of the covering. Furthermore, the condenser of the heat pump comprises one or several condenser elements distributed in the rooms of the house, said elements being arranged to be in direct contact with the air of the rooms without any heat transmittance medium whatsoever.

The covering of the heating device comprises, according to a preferred embodiment of the invention, a roof or a part of a roof, disposed above the building. According to one particularly preferred embodiment of the invention the roof of the building comprises at least two roof sections being inclined towards each other, under which sections a space is formed, which communicates with the exterior air by means of air gaps, this embodiment being characterized by the fact that the evaporator is placed in the space under the roof sections. According to another preferred embodiment of the invention the evaporator is placed on one of the sunlit walls of the building and below the eaves, the wall and the eaves forming the covering, which protects from wind and weather. Preferably, solar reflectors are placed on the wall behind the evaporator.

In another preferred embodiment of the invention the evaporator and the covering surrounding the evaporator are portions of a solar collector, possibly provided with a translucent protective layer, e.g a plate of glass or a transparent plastic material. The solar heat absorbed by the solar collector is transmitted to the evaporator. Preferably, solar reflectors are suitably arranged on the wall or the roof besides the solar collector.

A mapor advantage of the heating device of the present invention is that the pump height can be kept at a low level e.g below 50 C, chiefly due to the possibility of greatly extending the surface of the condenser element or elements but also the evaporator surface. In a particularly preferred embodiment of the invention the condenser element or elements are placed at the ceilings of the building. By this arrangement and due to the low temperature of the condenser element or elements the air convection of the rooms will become almost nonexistent and heat radiation will be predominant compared with thermal convection by air circulation, thus making it possible to keep the room temperature low while at the- same time the heating economy of the building is improved and nevertheless the comfort is maintained.

The invention is described hereinafter in detail with reference to the attached drawings, wherein:

Fig. 1 diagrammatically shows a cross section of the heating device of a small house according to the invention;

Figs. 2 and 3 shows two preferred embodiments of the condenser of the heat pump of the heating device of the invention;

Fig. 4 shows two suitable embodiments of the covering protecting from wind and weather, while

Fig. 5 shows how excess heat of the gaseous heat carrier can be utilized for water heating.

Referring to Fig. 1, a preferred embodiment of the invention is shown disclosing an arrangement in a small house having one and a half floors. The heating device consists of a heat pump, which in a familiar way comprises an evaporator 1 designed to evaporize a heat carrier, which is circulated in a closed pipe loop 5 by means of a compressor 4 switched into said loop. Downstreams of the compressor in the loop a condenser 3 is switched in as well as a pressure reducing valve 2.

According to the invention the heat pump of the heating device is provided with one single loop 5 for the heat carrier of the system. The evaporator 1 is arranged to absorb heat directly from air outside the space to be heated, while the condenser 3 is arranged to give off heat directly to the air in the space to be heated. Thus, no intermediate heat exchange with additional media, exists, while this is the case with known heat pump devices in buildings .

According to the invention the condenser of the heat pump is used as a radiator. Hence, the condenser of the heat pump is devided into several separate condenser elements 3a-3c in series or in parallel, which ire arranged to interact directly with the air in the space to be heated.

The utilization of the condenser elements 3a-3c as radiators results in one additional advantage. The condensation in the condenser elements occurs at one and the same temperature and thus all of the condenser elements (radiators) will have the same temperature. This is different from the case of customary water radiators connected in series, in which the temperature falls, successively from the first to the last radiator.

The condenser elements are suitably distributed in the space or the rooms to be heated and according to the invention they are preferably installed at the ceiling of the space to be heated, possibly at a little distance from the ceiling. Referring to Figs. 2 and 3, suitable embodiments of condenser elements are shown. It has been found that known embodiments of condensers, which are used in refrigerators and freezing plants, advantageously can be used in this connection. However, the embodiment according to Fig. 3 is preferred. It is more attractive and consists of two oppositely disposed parallel distributing pipes and parallel pipes disposed between the distribution pipes. The pipes between the distributing pipes are provided with transversal rods on two sides to increase the heat dissipating area. The embodiment according to Fig. 3 is the preferred one, but the condenser elements may be designed in many ways, provided the contact surface as regards the surrounding air is large.

According to the invention the condenser elements are installed at or close to the ceiling of the space to be heated and this results in the advantage that heat energy is transmitted from the condenser to said space mainly due to radiation with the result that air convection in the space is reduced.

According to the invention the evaporator 1 is surrounded by a covering which forms a roof 10 above the evaporator. In this way an air cushion or pocket is enclosed below the roof 10. The presence of the covering also prevents warm air from easy escape, when the evaporator is being defrosted and the weather is windy.

According to the preferred embodiment shown in Fig. 1 the evaporator 1 is installed below the main roof 10 of the small house and where it is possible for a person to climb or crawl.

The air pocket formed below the roof 10 is heated by heat energy radiating and escaping from the building. The air pocket is also heated indirectly by solar radiation striking the roof 10.

This heat is utilized by the evaporator 1 and is dissipated only in a minor measure due to the required selfventilation under the roof 10, shown by arrows 8 and 9.

The self-ventilation under the roof is utilized according to the invention to bring the exterior air in touch with the evaporator, thus making it possible for the heat of the exterior air to be transmitted to the evaporator. As shown in this embodiment of the roof 10, the exterior air (arrow 8) flows through a thin gap, which mainly is extended over the whole roof and the upper limiting surface of which is the bottom surface of the room 10. When the roof 10 is heated by the sun, the heat of the roof is easily transmitted to the passing stream 8 of exterior air. Thanks to the fact that the air flows by itself under the roof and ventilates the space, in which the evaporator is placed, a fan is not required to transport exterior air to the evaporator. Thus, more energy can be saved.

Thus, the heating device according to the present invention includes only one unit, to which energy must be fed, namely the compressor 4 , which is controlled by a unit (not shown) in accordance with the heat requirement of the house.

In order to utilize the heat energy of the waste air from the heated rooms of the house, ventilation ducts 6 and 7 from the various rooms discharge the waste air into the space, where the evaporator 1 is placed. Thus, the heat energy of the waste air will be absorbed by the evaporator.

The above-described installation of the evaporator 1 above the space of the building to be heated is probably the most advantageous, said covering functioning as an air collecting pocket over the evaporator while at the same time functioning as the roof 10 of the house. However, especially in case the space or house to be heated is provided with a flat roof and thus is not provided with any space to climb or crawl into under the roof, the evaporator can be installed on the outside of the roof or on the outside of the wall, e.g under a roof portion extending from the wall, an eaves, in which latter case preferably a covering at least partially enclose the evaporator and protects it from wind and rain. With these embodiments it will be possible to utilize solar energy in a direct fashion while at the same time the heat of exterior air and the heat of other media (see account given above) can be utilized.

Fig. 4 shows a house provided with two solar collectors according to the invention, one collector on a sunlit portion of the roof 15 of the house and on one of the sunlit walls 25 of the house.

Exterior air flows through the inlet 13 of the solar collector on the roof, is cooled, when it passes the surface of the evaporator 11, grows heavier and escapes through the outlet 14. Heated air from other sources, e.g waste air and attic air, may also be forced to pass the evaporator 11 and give off their heat to the gas in the evaporator (not shown) thanks to the cool temperature of the evaporator and a chimney effect. The covering around the evaporator possibly includes a transparent protective layer (not shown) in front of the evaporator, e.g a plate of glass or a transparent plastic material, with the result that solar heat can be directly absorbed by the evaporator 11.

Exterior air also flows into the solar collector on the wall 25, namely through the opening 23 in a covering, which in this case includes the eaves 22 a and a particular transparent shield 22 b protecting from wind and rain and placed in front of the evaporator 21. The exterior air, which is cooled by the evaporator 21 and thus grows heavy, and possibly warm air from other sources and cooled in the solar collector in the same fashion, moves downwards and escapes through the outlet 24. In case a protecting shield 22 b is not used, the flow of exterior air and warm air from other sources down to the evaporator 21 and the flow of cooled air down from the evaporator will mainly be the same as described. Solar heat is absorbed directly by the evaporator. The amount of solar radiation, which passes by the evapora- tor 21, is reflected against the evaporator by the reflector 26 and thus, the energy of solar radiation striking the wall 25 can be better utilized as heat in the heating device of the invention.

In the above-described heating device it is only necessary to pump the heat carrier of the heat pump to a temperature of about 25-30º C, provided the device and its condenser elements 3a-c are correctly dimensioned. This temperature is considerably lower than about 60 C, in which working temperature the pumping must result to be efficient in known heat pump systems, which use heat exchange with air or water carriers to distribute the heat to the rooms of the house.

The heating device of the present invention is dimensioned to meet the basic heat requirements of a building or a space. In order to provide optional additional heat a multitude of arrangements are possible. Radiators to provide additional heat should be installed a long distance from the condenser elements of the heat pump to prevent the latter from being influenced by the additional radiators. The heat pump in the device according to the invention can then be driven at a constant pump height, regardless of the temperature of the exterior air, which influences the evaporator. Hence, the heat factor of the heat pump can be kept at a constant level, when the temperature of the exterior air is lowered, also when the capacity of the heat pump is reduced due to the lower temperature of the exterior air.

As far as the perferred embodiment of the heat pump device of the invention goes, in which the covering protecting from wind and rain is a roof 10 placed above the building, the defrosting of the evaporator 1 can be accomplished rapidly, suitably by bypassing the condenser 3. Since the evaporator 1 is at least partly enclosed and provided with an overhead covering, the heat, which is continuously fed into this covering (the crawling space under the roof), will remain there and assist during the defrosting to melt the outside layers of the ice on the evaporator. The location of the evaporator also contributes to the fact that the ice formed on the evaporator will not grow so rapidly compared with the ice growing on an evaporator located in the basement of the small house or building to be heated or outside it.

Thp evaporator 1 shown in Fig. 1 is a unit at some distance from the roof of the small house. However, the evaporator can also be suspended from the rafters of the roof and it is preferably devided into at least two long units, installed along the roof.

In reference to Fig. 5, a preferred embodiment of the heating device according to the present invention is shown, as regards its compressor unit 4 and duct 5 between the compressor and condenser unit 3. Compressor 4 is positioned on a water tank 16. Between compressor 4 and duct 5 leading to condenser portion 3 b a heat exchanger 17 is connected. Heat exchanger 17 is placed in the water of water tank 16. The gas, which leaves compressor 4, is always overheated and thus, it is not suitable to let it directly enter condenser portions 3a och 3b. The gas should not have a higher temperature than its condensation temperature in these portions, because then the temperature will be even and the heat radiation comfortable. When the overheated gas is led from compressor 4 through heat exchanger 17 two advantages are attained: The heat of the overheated gas can be utilized tp heat water for household purposes and the gas is cooled to its condensation temperature or substantially to that temperature. A noise problem is also solved, when compressor 4 is positioned on water tank 16. The compressor readily emits annoying noise. When the compressor is positioned on the water tank, sound resonance phenomena decrease.

Claims

We claim:

1. A heating device comprising a heat pump to heat the rooms of a building, the evaporator (1) of the heat pump being placed outside the building and enclosed by a covering (10) protecting from wind and rain, into which exterior air, waste air and/or warm air from other sources, e.g solar heated air, flows and passes by the evaporator, chiefly due to the fact, that that amount of air, which at any moment surrounds the evaporator (1) directly and without any assistance of a heat transmitting medium gives off its heat to the evaporator (1), is cooled and moves downwards and out of the covering (10), the condenser (3) of the heat pump comprising one or several condenser elements (3a, 3b) distributed in the rooms of the building, said elements being in direct contact with the air in the rooms without any assistance of a heat transmitting medium.

2. A heating device according to claim 1, wherein said covering (10) is a roof (10) or a portion of a roof above said building.

3. A heat device according to claim 2, wherein said roof of the building consists of at least two portions (10) , inclined towards each other, under which portions a space is formed, which by means of air gaps (8) communicates with the exterior of the building, the improvment being that the evaporator (1) is placed in said space.

4. A heat device according to claim 3, wherein the exterior air before its passage by the evaporator (1) is forced to pass one or several thin gaps (8) adjacent the roof (I0), which results in that solar heat absorbed in the roof can be given off to the passing exterior air and utilized in the heating device.

5. A heating device according to claim 2, wherein the evaporator (21) is placed on one of the sunlit walls (25) of the building and under the eaves (22a), preferably with one or several solar reflectors (26) placed on the wall (25) behind the evaporator (21).

6. A heating device according to claim 1, wherein the evaporator (11) and said covering (12) are integrated portions of a solar collector, possibly provided with a transparent protective layer, e.g a plate of glass or a transparent plastic material, the- evaporator absorbing solar, heat, the heat of exterior air etc .

7. A heating device according to any of claims 1-6, wherein supplementary heating elements, e.g electric radiators, are installed in the building, the improvement being that said condenser elements (3) are placed at quite a long distance from said supplementary heating elements, not to be influenced by them.

8. A heating device according to claim 7, wherein said condenser elements are installed at the ceiling of the rooms in the building.

9. A heating device according to any of claims 1-8, wherein the compressor (4) of the heat pump is positioned on a water tank (16), a heat exchanger (17) is connected between the compressor (4) and the duct (5) to the condenser portion (3b), the heat exchanger (17) is placed in water in the water tank (16), the overheated gaseous heat carrier from the outlet of the compressor (4) gives off its excess heat to the water in the water tank (16), when the heat carrier flows through the heat exchanger (17), and wherein the temperature of the gaseous heat carrier accordingly is lowered to its condensation temperature or substantially to this temperature, before it enters the condenser portion (3b) .