SE543989C2 - An apparatus and a method for heat supply to buildings - Google Patents

Abstract

The invention relates to a method and a heat pump arrangement for use with a heat pump system comprising a,an evaporator (3), a compressor (1), a condenser (9), an under cooler (10) and a throttling valve (2) in a transfer loop (100),said transfer loop (100) having a heat transfer fluid, heated up by means of a primary heating loop (200) and arranged to give off heat to a first liquid flow (400) via said condenser (9) and to second liquid flow (500) via a under cooler (10), said primary heating loop (200) comprising a heat exchanger (4), a pump (6) and a part (202) giving said heat to said condenser (9),wherein said first liquid flow (400) is arranged to circulate through a heating system of a building (8), having a warm water vessel (121) arranged to supply heat water (VV),wherein the water (VV) in said warm water vessel (121) is also arranged to extract heat from said first liquid flow (400),wherein,a preheating vessel (131) is arranged to preheat cold incoming water (KV) prior to entry in said warm water vessel (121), and,one or more de-icing vessel/s (17, 130) connected to a loop (500) arranged to extract heat from said transfer loop (100) via an under cooler (10).

Description

AN APPARATUS AND A METHOD FOR HEAT SUPPLY TO BUILDINGS FIELD OF THE INVENTION The present invention relates to an apparatus and a method in which heat taken from air is used to provide heat to buildings, and especially an easily removable and movable arrangement therefore.

BACKGROUND OF THE INVENTION In order to improve efficiency of heating systems it is generally known to take advantage of heat pumps, e.g. to supply heat to a building. From WO 200704 there is known a system including a heat pump with an evaporator and a condenser in which, in operation, a heat transfer medium in a heat transfer circuit that is heated up by means of the evaporator and a compressor is arranged to, at least in a heating mode, give off heat to a first liquid flow via a first heat exchanger part, wherein said system further includes a second heat exchanger part to, at least in a heating mode, give off heat to a second liquid flow, wherein said second liquid flow is arranged to circulate through a heat emission system, wherein the device includes means for, at least in a heating mode, heat water in a water reservoir, wherein said reservoir includes an inlet for entering water to be heated and an outlet for discharging heated water, wherein, at least in a heating mode, the water in the reservoir is heated by means of said first liquid flow. A closed circuit, separated from said heat emission system, is used to circulate said first liquid flow through said first heat exchanger part, wherein the circuit for heat emission passes through the water reservoir, which further allows that the liquid flow can be heated to a high temperature in the first heat exchanger part, with the result that also the water in the water reservoir also can be heated to a high temperature.

SUMMARY OF THE INVENTION The inventive apparatus comprises an efficient heat pump arrangement as defined in claim 1.

According to further aspect according to the invention it relates to a heat pump arrangement that is mobile in accordance with claim 2.

Thanks to the invention an efficient heat pump arrangement is provided that is very flexible, i.e. may provide heat in different combinations depending on need/desire, and that may efficiently supply heat taken from ambient air also in very cold climate.

Thanks to the ability of having the heat pump arrangement mobile/movable many advantages are gained regarding different kind of needs that may have to be fulfilled regarding various buildings, e.g. to supply extra heat to a radiator system, underfloor heating loop systems and/or fan coil unit systems and/or a hot water system, or a combination of one or more systems of such kinds.

According to a further aspect according Lo the invention it relates to a heat pump arrangement that may extract sufficient heat and that may controllably recirculate a part of that heat to efficiently depress ice formation and/or to preheat cold water.

BRIEF DESCRIPTION OF DRAWINGS In the following the invention will be described with reference to the enclosed drawing, wherein Fig. 1 shows a schematic view of the basic functions in accordance with the invention, superimposed on top of an enthalpy in diagram, Fig. 2 shows a schematic layout of a first embodiment, in accordance with the invention, Fig. 3 shows an exemplary solution in accordance with the invention wherein a container is used to provide a mobile heat pump installation, Fig. 4 is a view from another perspective of the container in Fig. 3, Fig. 5 shows a schematic view of the second embodiment in accordance with the invention, Fig. 6 shows an exemplary installation in accordance with the invention, wherein the working principle shown in Fig. 5 is installed in a container, and Fig. 7 shows another perspective view of the container in Fig. 6.

DETAILED DESCRIPTION In Fig. 1 there is shown an enthalpy diagram, as is well known in the art, for a transfer medium used for carrying out the invention, e.g. R134a, which has constant evaporating and condensing temperatures. Within the diagram there is shown a marked area, presenting lines A, B, C, D of the working cycle used in accordance with one embodiment of the invention and essential parts of the system. The lower line A extends horizontally from a left-hand comer positioned on the curve L that defines the dew point, i.e. the border between 100 % liquid and a mixture of gas and liquid. Basically, the transformation along line A is achieved by means of interaction between a primary heating loop 200 and a transfer loop 100.

In the example presented in Fig. 1 the gasification temperature, t2, for this lower line A is e.g. about -5° C and the pressure, P1, e.g. about 6 to 7 bans. The line A extends all the way through and passes the zone of a mixture of gas and liquid (between L and G), such that the right-hand comer is positioned within the pure gas zone, i.e. on the right-hand side of the border line G between mixture of gas and liquid and pure gas. This part of the process is achieved by means of gasification heat exchanger 3 that can supply sufficient energy to the liquid in a tubing therein 101, of the loop 100, to transform it from liquid at the entrance to gas at the outlet, having a temperature t4that is higher than t2, e.g. of about 0° C. Thereafter the gas is compressed by a compressor 1, to a higher pressure, P2. During this process step the working cycle follows line B. Accordingly the compressor increases the pressure of the gas from Pi,e.g. about 6 to 7 bars, to P2,e.g. about 30 bars, and at the same time also increases the temperature from t4, e.g. about -5° C to t3, e.g. about 80° C, which are the values at upper right-hand comer. Here it follows the upper horizontal line C, which presents a condensation line at t1, e.g. at around 35° C. Accordingly the energy of the heated and pressurized gas is taken out along line C, which is accomplished by the use of three different, sequential cooling heat exchangers 7, 9, 10. It can be noted that preferably all the cooling heat exchangers 7, 9, 10 are counter current heat exchangers.

In the first one, a hot gas cooler 7 the hot gas is cooled from t3to a temperature t6slightly above the condensation temperature t1, e.g. to temperatures like the above 35° C, e.g. to about 40° C. This is taken out as heat in the secondary tubing 300, containing heating water, in the hot gas cooler 7. The incoming heating water to the hot gas cooler 7, via line 301 is supplied in the form of preheated heating water from line 402 belonging to the secondary tubing 400 an intemiediate heat exchanger, i.e. a condenser 9. In the condenser 9 the cooled gases from line 102 will start condensing in line 103, wherein the condensing temperature t1, e.g. 35° C will be reached. Moving left wise along line C a larger and larger amount of the gas will condensate and at the end of the condenser 9 all of the fluid in the loop 100 will be in liquid state, and to a temperature t7slightly below the saturation temperature ti. The inlet to the condenser 9 is heating water (to be heated) that may be supplied from two different sources, 403 and 401, respectively, which will be explained more in detail below. The final stage of the cooling process is performed by an under cooler 10, wherein liquid in the primary tubing 104 will be cooled further to t5by cooling liquid in a further loop 500, as will be explained more in detail below, to thereby reach the left-hand endpoint of line C.

After leaving the tubing 104 of the under cooler 10 the liquid in loop 100 passes through a throttle valve 2, which reduces the pressure from p2to p1, e.g. from about 22 to 25 bars to about 6 to 7 bars, which will cause the chosen fluid to be in a state where it reaches the border line L between purely liquid phase and mixture of liquid and gas phase, which is at t2, e.g. a temperature at about -5° C. As is evident from the above the fluid chosen for the working loop, i.e. in the primary tubing 100 is a fluid having a freezing point far below 0° C, preferably having a boiling point below -20° C. A preferred fluid is a Hydrofluorocarbons, e.g. a standard media such as R134a, R407C or R410A. (As well understood by the person skilled in the art the use of a capital letter last indicates that it is a mixture, which in turn indicates that the evaporating and condensing lines will glide). A preferred fluid in the de-icing loop 500 and the second loop 200, respectively, may be a mixture of ethylene glycol and water.

Fig. 1 further shows that the gasification heat exchanger 3 that transforms the fluid along line A has a secondary loop 200 connected thereto that supplies heat to the gasification heat exchanger 3 by means of an air heat exchanger 4, through which surrounding air is forced by means of a fan. The gasification heat exchanger 3 preferably is in the form of a plate heat exchanger which may reliably distribute heat to the mixture of gas and liquid in the gasification heat exchanger 3. The air heat exchanger 4 preferably is in the form of a fin heat exchanger providing a large transfer area for delivering the heat from the passing air to the tubing 201 within the air heat exchanger 4. A pump 6 is arranged to control the flow in the loop 200 and an appropriate flow through the tubing 202 in the gasification heat exchanger 3. The temperature t8of the fluid in the tubing therein 101 of the air heat exchanger 4, will have about the same temperature t2as the inflowing liquid into the gasification heat exchanger 3, e.g. about -3° C. At the outlet of the air heat exchanger 4 the temperature t9of the fluid in line 202 will have increased, e.g. to about 5° C.

As schematically shown in Fig. 1 the working cycle presented above is used to produce heat that is to be supplied to a building 8. As will be explained more in detail below the different parts needed for producing the heat that is to be supplied to the building 8 are preferably placed in a mobile unit 700 including all equipment needed to perform the working cycle.

Further equipment used to perform the working cycle are vessels 121, 131, and 120, 130 (see Fig. 2) and 17 (see Fig. 5), respectively, assisting in performing a working cycle as described above in relation to Fig. 1. It is to be noted that line 401 depicts the inlet of the inlet fluid to the condenser 9 that is supplied from the heating installation of the building 8 and that the line 402 depicts the heated heating liquid that is supplied to the heating loop 400 of the building 8. One of the vessels is a heat water vessel 121, that supplies the building 8 with heat water VY. The function of the other vessels will be explained more in detail below.

Moreover, as is well known in the field that heat pump system is provided with one or more control units (not shown here, but indicated in Figs. 6 and 7 as 710, 711), that controls and monitors various functions in the heat pump. Examples of such functions can be measuring, setting, adjusting and/or monitoring of parts of the system (c.g. compressor), e.g. in relation to indoor and outdoor temperatures, adjustment of heat curves, control of room temperatures, etc.

In Fig. 2 there is shown a schematic lay out of an application within a mobile unit 700 using the basic principles of a working cycle as shown in Fig. 1. There is shown an embodiment where there is a first unit 12, i.a. suppling heat water VV to the building 8, in the form of an outer casing 120 enclosing the heat water vessel 121. In the space 12A between the outer casings 120 and the heat water vessel 121 circulates heating liquid used for the heating installation of the building 8. This heating liquid enters into the mobile unit 700 via line 401 and thereafter moves in counter current in the condenser 9 and re-enters into the building by line 402. The flow in this heating loop 400 is assisted by means of a pump 15 in the supply line 402. As is shown in the figure heating liquid may also be added to line 401 via line 403, which is the outflow from the intermediate heating space 12A of the first unit 12. Heating liquid may be supplied to that space 12A via line 302. A branch line 301 may be used to branch off heating liquid from the supply line 402 before reaching the output pump 15. Liquid in the branch line 301 enters into the hot gas cooler 7. A branch line pump 14 is used to move heating liquid in and out of the space 12A. Accordingly, extra heat may be supplied to the heating liquid by means of extracting heat from the hot gas cooler 7, supplying it to the intermediate space 12A, where it may transfer heat to the heat water vessel 121 in direct contact therewith. The inner space 12B of the heat water vessel 121 is filled with heat water W intended to enable supply of extra heat water VV to the building 8.

The supply of the water to the heat water space 12B is achieved by a water line PV that supplies pre-heated water from an internal space 13B of a second unit. The second unit 13 is also a vessel containing an outer casing 130 and an inner vessel 131. As already mentioned the inner casing encloses a space 13B containing the water that eventually will be supplied as heat water W to the building. The supply to that cold-water space 13B is achieved by means of a cold-water line KV.

The space 13A in the second unit 13 contains the fluid used in the heat exchanging process in the secondary tubing 500 in the cooling heat exchanger 10, and also in the primary tubing of the heat exchanger loop 200 and circulating within the air heat exchanger 600 and the gasification heat exchanger 3. The latter heat exchanger loop 200 is supplied from the first vessel 13 by means of a supply line 601 and then supplied to the tubing loop 200 prior to the entry into the air heat exchanger 4. Supply from the heat exchanger loop 200 to the first vessel 13 may adjustably be controlled by means of a control valve 11 positioned after a pump 6 that is installed after the outlet from the air heat exchanger 4 and before the gasification heat exchanger 3. The supply is arranged for via line 602 to the intermediate space 13A of the second vessel 13.

In an exemplary installation in accordance with the invention it is assumed that the surrounding temperature of the air that is forced through the air heat exchanger 4 is 7° C, running at about 70% (and 100%, respectively). The compressor 1 has a power supply of about 67 kW, the condensation temperature, line C, is chosen to be 35° C (35° C), and the gasification temperature, line A, is chosen to be -5° C (-6° C). Ethylene glycol is used in the intermediate space 13A in the second vessel 13. The temperature of the supplied heating liquid from the building 8 via line 401 is assumed to be 28° C. The control valve 11 is controlled to arrange for a temperature of about -3° C (-4° C) of the ethylene glycol at the entry of the air heat exchanger 4. In the air heat exchanger 4 the ethylene glycol will be heated to a temperature of about 5° C (5° C) when leaving the air heat exchanger. The heat supplied to the gasification heat exchanger 3 will be sufficient, thanks to the dimension of the gasification heat exchanger, preferably in the form of a plate heat exchanger, to transform the heat exchange fluid from a liquid state at -5° C (-6° C) to a gasified state of about 3° C (2° C) in line 101. Thereafter the compressor 1 transforms the gas from pi to p2 resulting in a temperature of about 73° C (77° C). In the hot gas cooler 7, the temperature in that part 102 of the first loop 100 will drop from about 73° C (77° C) to about 40° C (40° C) in counter current heat exchange with heating liquid in part 300, implying that the heating liquid supplied to the intermediate space 12A of the first vessel may have a temperature near or at about 70° C (75° C). The actual temperature of the heating liquid supplied to the intermediate space 12A, is dependent on the flow in part 300, i.e. the speed of the pump 14. A sufficiently high flow will bring down the temperature, but at the same time supply more heat to the intermediate space 12 A. The heat of the liquid in the intermediate space 12A will transfer heat to the internal space 12B containing heat water VV.

Accordingly this design enables extra production of heat water VV at occasions when that may be needed. Thanks to the design the extra production of heat water VV may be achieved without any significant negative consequence on the system as a whole.

The condenser 9 will increase the temperature of the heating liquid supplied via line 401 at temperature of about 28° C (28° C) to a temperature at about 35° C (35° C) that is supplied to the building via line 402. The cooling heat exchanger 10 will affect the liquid in path 104 to move from about 35° C to about 15° C. Then when throttling the liquid in the first loop 100 in the throttle valve 2 it will change the pressure from p2 to pi resulting in a liquid at about 5° C (-6° C), which enters into the gasification heat exchanger 3. The heat taken out from the cooling heat exchanger 10 is supplied to the ethylene glycol in the intermediate space 13 A in the second unit 13 via line 502 and a pump 16. This heat is then transferred to the internal space 13B of the second vessel 131 containing cold water KV that is then pre-heated before entering into the inner space 12B of the first vessel 121 via line PV. In an exemplary embodiment the cold water KV is about 10° C and is about 30° C (35° C) after pre-heating, enabling supply of heat water W at 70° C (75° C).

Thanks to the control valve 11 and connection of the heat exchanger loop 200 to the intermediate space 13A of the first vessel it is possible to switch the flow and get a desired temperature within the air heat exchanger 4, to arrange for de-icing of the air hear exchanger 4. For instance, this function may be activated when the temperature difference between the ambient air and the temperature on the line 200 is bigger than a given pre-set value, i.e. providing an indication that there is too much ice to obtain efficient heat transfer in the air heat exchanger 4. The control valve 11 may then open connection with line 602 and the relatively warm liquid in the intermediate space 13 A will flow via line 601 into the air hear exchanger 4 for de-icing thereof. Thanks to the arrangement of the liquid in the intermediate space 13A to both enable preheating of cold water KV and de-icing of the air heat exchanger 4, the de-icing function is established in a totally reliable manner and more or less without any loss.

In a preferred embodiment the pump 14 supplying the intermediate space 12 A with heated heating liquid via line 302, is a variable speed pump 14 that may supply variable flow, e.g. to control the flow through the heat gas exchanger 7 to have all or at least the majority of the condensation taking place in the condenser 9.

Further, the proposed setup ensures that the water entering the hot gas exchanger 7, is warmer than the average temperature in the condenser, 9. Most existing hot gas exchanger setups have a separate flow over the final tap water tank trough the hot gas exchanger. If this tank gets cold water and the flow heating up this water is to high it will result in cold water entering the hot gas exchanger. If the average temperature of the water in the hot gas exchanger is colder than the average temperature of the water in the condenser the gas will condense in the hot gas exchanger instead of the condenser. The dimensioning of the hot gas exchanger is normally only 10-15% of the area of the condenser due to cost restraint and the intended effect utilization of 10-15%. If all condensation happens in the hot gas exchanger almost all effect is transferred in this exchanger. If this only have 10-15% of needed area this effect will be transferred with a 7-10 times higher temperature difference leading to a much lower coefficient of performance, COP. Since the proposed setup ensures that the water entering the hot gas exchanger 7, is warmer than the average temperature in the condenser 9, the proposed setup will never experience the above mentioned problem.

A further beneficial aspect according to the invention is that preferably also the pump 15 that supplies heating liquid to the building 8 is also variable speed pump.

(Alternatively, an on/off controlled pump). An advantage with the design according to the invention is that when the pump 15 is turned off the heat from the condenser 9 extracted in line 402 will also be supplied to the heat gas exchanger 7, which enables a higher flow and larger amounts of heat to be transferred to the heat water tank 121. Accordingly, by this design, it is possible to momentarily supply less heat to the heating installation of the building 8 and instead supply the extra heat from the condenser 9 to the heat water tank 121, thereby temporarily enabling a larger flow of heat water VV to be taken out at a desired temperature.

The present invention also has the advantage that the heating system of the building 8 can be kept in circulation all the time. By controlling various control parameters, the heating process can at all times be controlled using the heat pump control unit/s.

Examples of control parameters can include of one or more of: - the temperatures of the flowing media before and after the respective heat exchanger part, 8,9,10, - the flow of the heating system of the building 8, - the flow of the first loop 100 and/or second loop 200, respectively - one or more temperatures (e.g. at different positions) in the vessels 121, 131, 120/130/17, - the temperature of the hot gas, - the withdrawal of hot water VV, - the pressure of one or more of the mediums in the loops 100, 200, 500, respectively, - the power delivered by the compressor 1, - the setting of the throttle valve 2.

Idle control can thus be arranged to give priority to different tilings at different times In Figs. 3 and 4 are shown perspective views of a preferred manner of arranging movability of an arrangement in accordance with the invention. There is shown that a parallel epipetric structure 700 is used to include all needed equipment for the mobile heat arrangement. Preferably a container 700 of standard format is used as a basic framework. The container 700 is rebuilt in some respects, e.g. to arrange for doors 703, preferably at one short end thereof. Further, there is also arranged for air intake 708, preferably at another short end 708. A dividing wall 702 is arranged to divide the container space into a first, preferably larger, space 704 and a second, preferably smaller, space 705. Within the second space 705 a fan 5 is arranged in connection with a support and seal wall 706. The fan 5 provides for sucking air into this space 705 via the air heat exchanger 4, that preferably is arranged to have a size fitting to one short end 708. A long one of the long sides of the container there is arranged a wall part 701 that enable air to pass out from the space 705, e.g. in a form of a wall of mesh.

Within the larger space 704 there are positioned the first and second units 12, 13.

Further also the other parts of needed equipment described in Figs. 1 and 2 are also preferably positioned in this space 704. According to a preferred embodiment some parts of the equipment 1, 3, 7, 9, 10 are positioned on an easy removable carrier 707, e.g. in a form of a pallet. Thanks to the use of easily exchangeable carrier 707 and adapted quick couplings (not shown) the whole removable carrier 707 may quickly and easily be exchanged for a new carrier 707. As is evident this makes it possible to maintain the heat arrangement in good working condition by timely exchange of the whole movable carrier 707 in order to avoid problems due to brake-down or need of maintenance of any of the parts 1, 3, 7, 9, 10 included on the removable carrier 707. Further this provides the advantage that repair and maintenance may be performed in a facility especially suited for this purpose, and not in situ as is often needed with other kind of installations.

In Fig, 5 there is shown an alternative embodiment of performing the working cycle in accordance with the invention. Most details are the same as those already shown and described in connection with Fig. 2 and therefore it will merely be a focus on changes in regard to this alternative embodiment. The main difference is that there is no use of doubled shelled units 12, 13, instead as shown in Fig. 5 singled shelled vessels 121, 131 are used in accordance with this preferred embodiment, which is a less costly installation. Further there is arranged a third vessel 17, replacing the intermediate space 13A used in Fig. 2. Accordingly, there is a separate vessel 17 for containing the ethylene glycol, which may be seen as a de-icing tank. Flaving the de-icing tank, 17, separated from the incoming cold water ensures that sufficient energy for de-icing may always be present in the de-icing tank, 17.

The basic work in principle is the same as been described above. However, thanks to the use of a spiral tubing 122 within the space 12B of the heat water tank 121 a more efficient transfer of the heat may be achieved of the heated heating liquid supplied via line 302 and taken out via line 403. Also, in relation to the ethylene glycol in the deicing tank 17 that is supplied via line 503 to the pre-heating tank 131 there is similar advantage since spiral tubing 132 may be used to efficiently transfer heat to the cold water KV within the pre-heating tank 131. Accordingly, the pre-heated water supplied via line PV to the heat water tank 121 may be more efficiently pre-heated prior to entry into the heat water tank 121.

In Figs. 6 and 7 there are shown perspective views of a mobile container 700 arranged with devices in accordance with the layout presented in Fig. 5. Since basic principles are similar for that shown in Figs. 6 and 7 as that shown in Figs. 3 and 4, a focus will merely be on changes. It is to be noted that the two vessels 121, 131 relate to single shelled vessels, and therefore may be larger than if placed within another casing.

Another difference is that the air outlet is provided in the roof of the container 700 by means of an outlet pipe 709. Further also the fan 5 is moved to be attached to the roof within the smaller space 705. In the larger space 704 there is used a removable carrier 707, as has already been described above. In Figs. 6 and 7 also control units 710, 711 are shown wherein preferably one of the control units 711 controlling the different items on the exchangeable carrier 707 is also attached to the removable carrier 707. The different items on the carrier are schematically marked out.

Further it is shown that an electrically powered supply device 18 may be used, to provide for the possibility to apply extra heat to the heating liquid in line 402 supplied to the building 8.

The deicing tank 17 is in this embodiment divided into two separate single shelled tanks 171, 172 in order to provide for sufficient volume and still fit well into the container 700. Here the two doors 703 are used on one of the short walls to enable easy access into the container from one of the short sides.

It is foreseen that this application may be the subject matter for numerous divisional applications, having claims focusing on different aspects of the inventive concept, e.g. one focusing on the aspect of an efficient heat pump system and another focusing on the aspect of an advantageous mobile heat pump arrangement. Further it is evident for the skilled person that the invention is not limited to what is described above but may be varied within the scope of the claims and further that the expression building must be given a broad interpretation. For instance, it is evident that the mobile unit itself as well as the different vessels may be provided in various configurations/shapes to suit different needs, but still fulfil the basic function of the invention. Further, it is evident that in some mobile installations there may be no desire to more than one heat exchanger besides the condenser 9, e.g. to not use a hot gas cooler. Moreover, the skilled person realizes that varying power of the compressor 1 may be used depending on need, but preferably the power of the compressor 1 is within the range of 50 to 100 kW, to suit a mobile unit of appropriate size of logistic reasons.

Claims (12)

1. Heat pump arrangement for use with a heat pump system comprising a, - an evaporator (3), a compressor (1), a condenser (9), an under cooler (10) and a throttling valve (2) in a transfer loop (100), - said transfer loop (100) having a heat transfer fluid, heated up by means of a primary heating loop (200) and arranged to give off heat to a first liquid flow (400) via said condenser (9) and to second liquid flow (500) via a under cooler (10), said primary heating loop (200) comprising a heat exchanger (4), a pump (6) and a part (202) giving said heat to said condenser (9), - wherein said first liquid flow (400) is arranged to circulate through a heating system of a building (8), having a warm water vessel (121) arranged to supply heat water (VV), wherein the water (W) in said warm water vessel (121) is also arranged to extract heat from said first liquid flow (400), characterised by, a preheating vessel (131) arranged to preheat cold incoming water (KV) prior to entry in said warm water vessel (121), and, one or more de-icing vessel/s (17, 130) connected to a loop (500) arranged to extract heat from said transfer loop (100) via an under cooler (10).

2. Heat pump arrangement according to claim 1, characterised in that said heat pump system is arranged within a mobile unit (700), wherein said heat exchanger is an air heat exchanger (4) attached to an outer part (708, 712) of said a mobile unit (700), wherein said air heat exchanger (4) is supplied with air by means of a fan (500) also attached to a part (704, 711) of said mobile unit (700).

3. Heat pump arrangement according to claim 2, characterised in that a dividing wall (702) is arranged to divide the mobile unit (700) into a first, preferably larger, space (704) and a second, preferably smaller, space (705), wherein most parts of the heat pump system are positioned in the first space (704) and the air heat exchanger (4) and fan (5) are positioned in the second space (705).

4. Heat pump arrangement according to claim 2 or 3, characterised in that some critical parts (1, 3, 7, 9, 10) of the heat pump system are positioned together on an easy removable carrier (707), preferably in the form of a pallet,

5. Heat pump arrangement according to claim 4, characterised in that said easy removable carrier (707) is positioned within said first space (704).

6. Heat pump arrangement according to any preceding claim, characterised in that said one or more de-icing vessel/s (17, 130) is in the form of at least one separate tank (17).

7. Heat pump arrangement according to claim 6, characterised in there is a plurality of separate de-icing tanks (171, 172), preferably having substantially the same size.

8. Heat pump arrangement according to any preceding claim, characterised by a hot gas cooler (7) arranged to pre-cool the fluid in gas form in the first loop (100) prior to entry in the condenser (9) and to provide heat to said warm water vessel (121).

9. Heat pump arrangement according to claim 8, characterised by a branch lines (301, 403) arranged to controllably connect said hot gas cooler (7) to said first liquid flow (400), wherein a first branch line (301) connects said hot gas cooler (7) via an output line (402) from the condenser (9) and a pump (14) in an output line (402) from the hot gas cooler (7) is arranged to control the flow and wherein a second branch line (403) connects a return flow to an input line (402) for the condenser (9).

10. Heat pump arrangement according to any preceding claim, characterised in that said second liquid flow (500) is connected to provide heat to said preheating vessel (131).

11. A method for heat supply to a building, comprising the steps of; providing a heat pump system comprising, o an evaporator (3), a compressor (1), a condenser (9), an under cooler (10) and a throttling valve (2) in a transfer loop (100), o said transfer loop (100) having a heat transfer fluid, heated up by means of a primary heating loop (200) and arranged to give off heat to a first liquid flow (400) via said condenser (9) and to second liquid flow (500) via a under cooler (10), o said primary heating loop (200) comprising a heat exchanger (4), a pump (6) and a part (202) giving said heat to said condenser (9), - circulating said first liquid flow (400) through a heating system of a building (8), having a warm water vessel (121) arranged to supply heat water (VV), wherein the water (VV) in said warm water vessel (121) is also arranged to extract heat from said first liquid flow (400), characterised by providing, - a preheating vessel (131) arranged to preheat cold incoming water (KV) prior to entry in said warm water vessel (121), and, one or more de-icing vessel/s (17, 130) connected to a loop (500) arranged to extract heat from said transfer loop (100) via an under cooler (10).

12. A method according to claim 11, wherein said heat pump system is arranged within a mobile unit (700), and providing said heat exchanger as an air heat exchanger (4) attached to an outer part (708, 712) of said a mobile unit (700).