DE2509965A1 - Heat pumps for room heaters - ensuring excess heat is supplied to a heat store - Google Patents

Abstract

The condensation heat from a heating pump system is fed into a heat store. During periods of high demand, the heating pumps remove the heat from the store, and raise it to the demanded temperature level. Both undercooled-and excess heat of the refrigeration machine are fed in. The heat retracted from summer air or solar energy is fed directly into the store, without pumps. In a multi-storey block of flats, or similar, each unit has its own heat pumps, to feed excess heat into a store, common to several units. During high demand, heat is extracted from the store, and supplied via a distribution conduit to the evaporators of the pumps, and raised to the demanded temperature.

Description

ing. igrad.J Herbert; R.A.M Ing. (Grad.) Dieter Fluck

If apartments or other rooms are heated with electrical resistance heaters, then there must be heat for every kilowatt hour over three kilowatt hours of primary energy can be fed to the power plant.

Various attempts have been made to heat living spaces by means of electrically driven heat pumps, whereby the groundwater, the soil or the heat loss contained in waste water or the exhaust air, e.g. from commercial companies, is used as a heat carrier The heat transfer medium mentioned is only available in sufficient quantities in special cases. In general, the heating could be provided by means of heat pumps if it were possible to use the outside air as a heat transfer medium in winter as well.

Two variants of the heat pump are known, the outside air as the heat carrier used:

One variant provides that the heat pump operates at any outside temperature, where space heating is necessary, i.e. even at very low outside temperatures, the outside air provides the required Removes heating heat and supplies it to the object to be heated. In the remainder of this discussion, the method is intended to be "always direct acting heat pump ". As the drawing Figure 1 shows, low outside temperatures are rare. The maximum electrical The power requirement of such a heat pump is therefore, compared with the annual electrical work required for its drive, large, i.e. the duration of use is short. If one now also considers that the performance figure of a heat pump is a function of the temperature difference is, by which the heat must be raised to a higher temperature level, then one recognizes that one after this process working heat pump at low outside temperatures of e.g. -13 0 (i.e. evaporation temperatures from -23 ° C to -28 ° G and Condensation temperatures of +60 G) for hot water heating with

low flow temperature of approx. 55 only. ₃₃₃

333-250

C a performance figure of 0.5-2

can provide, i.e. with 1 kWh of electrical drive work, 2 kWh of heat can be supplied to the heated object. Does the external

609839 / ÖU7

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temperature, then the coefficient of performance improves if the control system of the heat pump allows adaptation to the changed conditions. This causes a group of such operated heat pumps, e.g. controlled by two-point controllers, that the power requirement 'and the daily consumption of electrical Reduce work disproportionately with rising outside temperature, i.e. reduce it more sharply than with direct resistance heating. The resulting low annual usage time forces a high electricity price, which is profitable of the procedure at risk.

The second known variant of the heat pump, which extracts the required heat from the outside air, is described in the yearbook of heat recovery, 2nd edition, page 21, published by Vulkan Verlag Essen. This variant provides that the heat pump only at outside temperatures voni / ¹ - ^0C, the required heating provides O, at low outside temperatures assumes a second, additional "heating system which operates with storable energy, the heat supply, the method is referred to as a bivalent heat pump. As the drawing in Figure 1 shows, in Central Europe about 85 % of the years hot heat is generated at temperatures ^ <- 0 ° C. In this range, the heat pump can work with a better coefficient of performance ^ than at temperatures QT _n <0 ° C.

el

Assuming the same heat distribution system as in the first case, i.e. a maximum flow temperature of the hot water heating of 55 C, then with an outside temperature of 0 ° C, a flow temperature would be set of approx. 45 G, i.e. a condensation temperature of 50 ° C, and a Evaporation temperature at 0 C outside temperature of -5 ° C is sufficient. This would increase the performance figure to:

6 ^ 3

e £

would be assuming an average outside temperature of

ere:

323 ■ _
323-275.5 * ^υ ' ⁵ ~ ^' ⁴

The mean annual output of all heating days 0 ^u C - ^ '- 1p °

el

be based on the assumption of an average outside temperature +7.5 C in this range

λ π η η η γ γ

I D υ α α υ O

The heating, which is required at temperatures C \ f <0 ° C, would have to be provided by a special incinerator. The dependence on fuels would therefore only be reduced compared to today's heating habits, but not eliminated. In addition, all of the guard parts of combustion systems must be accepted and, in particular, the safety regulations applicable to fuel heating systems must be observed.

Also known is a process that is described in the "Yearbook of Heat Recovery", 2nd edition, page 15, Vulkan-Verlag Essen, is described and placed in a building in the small heat pumps and draw their heat from a pipe system whose heat transfer medium is approx. 25 ° G. A hot water storage tank is connected upstream of the pipe system, which is heated with fuel or electricity to temperatures of 80 ° C in order to provide the heat for the entire object. The disadvantage of this method is that the supercooling heat of the heat pumps is not used and is stored in the memory introduced, as well as that due to high storage temperatures, heat quantities only with large losses, i.e. practically not at all Months can be saved. After all, it is not possible to use the sun's or environmental heat to heat the in warm weather Refer to the memory content. Also, the method in the described arrangement is not suitable for heating heat from the To gain outside air.

The invention relates to a method which eliminates the aforementioned deficiency. With this method, the heat pump is designed in such a way that it operates in the range with the greatest frequency of outside temperatures, e.g. up to to temperature en (v - 0 G, the required heating work Q-, immediate

el Xl

bar is withdrawn from the outside air and fed into the heat distribution system. If the building's heat requirement is less than the amount of heat, that the heat pump provides, then the refrigerant cannot fully condense in the condenser of the heat pump Vapors are passed into a second condenser, through which the excess heat Q «· is fed into a latent heat accumulator, which can store heat over long periods of time with little loss at low temperatures, as the drawing in FIG. 2 shows.

An arrangement is particularly suitable in which the supercooling heat of the system is used, as this increases the performance figure cder

■ ■. - 4 -

609831/0441

Indirectly improved heat pump. By subcooling the refrigerant liquid to + 25 ° C to + 30 ° C in a downstream condenser or heat exchanger, the cooling capacity Q and thus also the heating capacity Q of the heat pump increases while the power consumption of the compressor remains the same. The subcooling heat that is withdrawn from the refrigerant in the downstream heat exchanger cannot be used directly for heating because the temperature level is too low; however, it can be introduced into the latent heat accumulator and stored there. If the outside temperature falls below the value O ⁰ C, then the heat pump partially or completely removes the required amount of heat from the latent heat store, as the drawing in FIG. 3 shows. In the drawing Figures 2 and 3 mean:

(Xj = the amount of heat extracted from the environment

Q = heat demand of the house

Qq = excess or undercooling heat or stored heat

1 = heat pump

E = electrical drive energy

6 = memory

In summer, when there is excess heat, the heat Qg- ,. the latent heat accumulator 6 is supplied and also that absorbed by the outdoor air heat exchanger Solar heat, possibly without the interposition of a heat pump, can be stored directly in the latent heat accumulator 6, as shown in the drawing Figure 4 shows.

Another advantageous variant of the invention is given in the arrangement according to FIG. Here, the heat pumps 1 give their heat of condensation to a buffer memory 27 for heating and to a hot water memory 30 for the G-erauchswarmwasserbildung. The excess or undercooling heat Q _n flows to the latent storage device 6. If necessary, the amount of heat Q _{Ts can be} taken from the memory 27 in order to defrost the outside air heat exchanger 2 in the event of icing.

The latent heat accumulator 6 of this process must have a lot of heat at a temperature level that is adapted to the environment and as low as possible Can store volume so that no significant heat loss occurs.

609838/0447 " ⁵ "

step. A suitable medium for this is water, which "is converted ^{into the solid state of aggregation when heat is removed at 0} ° C. and gives off 80 kcal / kg of heat.

In summer or in the transitional period, the ice would, for example, be caused by the supply of heat from the sun melted and the melt water partially heated. In the transition period of autumn when the heat pump is not full is busy, the meltwater heats up to around 50 ° G thanks to the excess or supercooling heat. Per kg of water is then A heat quantity of 80 + 50 = 130 kcal = 0.15 kWh is stored, which is used to cover the peak heat demand on very cold days with outside temperatures below 0 ° G is available.

The method according to the invention also ensures that the evaporator of the "heat pump with latent storage", in contrast to the always direct-acting heat pump, is never loaded with a heat transfer medium that is colder than e.g. 0 C. So lie the minimum and the average performance figure of the heat pump with latent storage is significantly higher than with the always direct-acting one Heat pump.

Assuming a future average apartment size in

ρ
Germany from 80 m living space, and assuming a heat requirement of 100 watts per square meter of living space on the coldest winter day in climate zone II (rty = -15 ° G) with thermally insulated construction, then the required caloric heating output on the coldest winter day is P = 8 kW . If one also assumes that the room temperature is lowered during the eight hours of the night, the result on the coldest winter day is a required caloric heating work of W _d = 8 (kW). 20 (h / d) = 160 kWh / d.

It is known from climate statistics that the days with mean outside temperatures of iP <0 ° G on average during extremely cold winters have a mean outside temperature of f \? _at ~ -5 ° C. (Not all days with fxp <0 G have a daily mean temperature'v ⁾ "= -15 ° G).

3 tbsp

The average daily work at very cold outside temperatures is = 22 ° G room temperature

fa "" fe -160 ²² - (->

²² - M5J * ⁷ *

In West Germany, according to long-term climate statistics, only a few days with low outside temperature in uninterrupted sequence;

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in climate zone II a maximum of 12 days; before a new cold spell There are always a number of warmer days during which the heat pump feeds excess or undercooling heat into the latent storage can. During the connected 12 very cold days, the following caloric heat quantity would be required for space heating:

Q _12d = 117. 12 = 1 400 kWh / WoE

With a performance figure of 6 = 3 (i.e. 1 kWh of electrical work plus 2 kWh of work withdrawn from the environment or the heat storage system would result in useful heat of 3 kWh) the amount to be stored is calculated Amount of heat too

Mi = 1 400 2zl ₌ 950 kWh / week
ap ο

The water mass m required for storage is thus ^m = 930 If! : 0.15 * g | = 6 200 kg / WoE and the storage volume V = 6.2 m

A cube-shaped, thermally insulated water storage tank, e.g. made of concrete should have an edge length s of:

s = 4 / 6.2 = 1.8m

The conditions in apartment buildings are particularly favorable if each apartment is assigned its own heat pump and controlled depending on the apartment's heat demand. The electricity consumption of the heat pump in question can then be billed via the apartment meter, so that the individual apartment owner has the opportunity to save heat. Every apartment heat pump would feed its excess or undercooling heat into the common latent storage unit and draw additional heat from the latent storage unit on very cold days. Experience has shown that in a residential building with heating power consumption measured and billed per apartment, on average only approx. 60 % of the theoretically required amount of heat is drawn on, even on very cold days, because not every room in every apartment is always fully heated. Under these conditions, for example, the frequently encountered eight-family dwelling has a storage volume of

V = 6.2 ^ g. 8 weeks .0.6 = 30 m ³

609838/0447 7 -

The internal dimensions of a cubic storage tank with a maximum height of 2.2 m be:

3.7 m by 3.7 m

The drawing Figure 6 shows the method according to the invention in an objective example for the Pail that the Subcooling heat is used:

Heat pump 1 extracts heat from the outside air via evaporator 2 and transfers it via condenser 3 to heating system 8, for example controlled by return admixture 7. Condenser 4 feeds the subcooling heat of the system into latent storage unit 6. If the outside temperature falls below the system's design value of e.g. O ⁰ C, then the three-way valves 9 and 10, which can also be replaced by solenoid valves, switch over the evaporation of the refrigerant to the evaporator 5, which extracts the required heat from the storage unit 6. This method also allows the heat to be taken from the storage tank during the nocturnal toast and returned through the condenser 4 at higher daytime outside temperatures.

Pigur 7 of the drawing shows a further variant of the invention. The heat exchanger 11 extracts the heat from the outside air and releases it it is transferred to a frost-resistant liquid circulated by pump 17, from which the heat is extracted in evaporator 2 by heat pump 1. A control device 12 monitors the system once to the effect that the heat pump according to the temperature sensor 13 (Heating water temperature) and 18 (outside temperature) determined heat demand of the building is controlled, on the other hand, that three-way valve 9 always when the frost-resistant liquid at point 15, i.e. after leaving the evaporator, is still warmer than the contents of the storage tank (Pühler 14) the frost-resistant liquid in the heat exchanger 5 of the memory 6 is reversed, so that the excess heat flows into the memory. This applies in particular to the downtime of the heat pump 1 in summer and, under certain circumstances, when it is milder Weather even when controller 12 has temporarily switched off the heat pump because the heating system 8 has sufficient heat. Circulation pump 16 ensures that no temperature stratification occurs in the memory 6. Valve 19 prevents the refrigerant at high Storage temperature flows through heat exchanger 4. If the outside temperature has dropped below the design value of e.g. 0 ° 0, then controls 12 the valves 9 and 20 so that the required

609838/0447

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Heat is withdrawn from the memory 6 via heat exchanger 5.

The execution of a heat pump system according to the invention in one Multi-storey house is shown in Figure 8 of the drawing. The heat pump is 1a on the ground floor, 1b on the first floor and 1c on the second floor arranged etc. Since the power requirement of the heat pump for an apartment is 3 TtW, each floor can have a hermetically sealed Aggregate can be assigned, which is installed directly in the apartment. There are over the heating systems 8a, 8b and 8c etc. from the required heat to the apartments. The heat pumps extract the heating flow and return lines 24 necessary heat and feed the supercooling heat via the heat exchanger 22 into the latent storage 6 by means of the pipe system 25. The heat pumps 1a to 1c are controlled by the controllers 26a to 26c controlled and only heat the apartments to the temperatures that the apartment owner wants and only when they do so wishes. The circulation pumps 17 and 21 ensure the transport of the heat transfer medium, the valves 9 and 20 in a similar manner to how described in Figure 8, can be controlled. The great advantage of this solution lies in addition to the described better individual controllability per apartment and the associated significant energy savings in the low flow temperature of the flow and return lines 24, the associated low distribution losses and the possibility of the supercooling heat in the latent storage feed via the line system 25, justified. Another advantageous variant of the invention is given when the heat pumps 1 bring their heat of condensation into a second memory 27, as Figure 9 of the drawing shows. In particular, If the heat pumps are controlled by two-position controllers, the memory 27 acts as a buffer. In the following it is to be used as a buffer memory are designated. The heating system and domestic hot water preparation can be used from it draw their warmth, and from it auc! the heat can be withdrawn to the heat exchanger 11, which is the outside: air removes heat, periodically freed from ice, like the drawing Figure 5, Figure 9 and Figure 10 shows.

The domestic hot water preparation can be realized by that a tube bundle or a boiler through which the service water

G09838 / 0U7 " ⁹ "

flows, be accommodated directly in the buffer tank 27, or that the warm water of the buffer tank through the double jacket a double jacket store is conducted. However, the solution in which the domestic hot water storage tank promises particular advantages 30 by its own condenser, which is in series with the condenser 28 of the memory 27, with supercooling heat is heated, and in times of peak demand for warm water (Bathing day) a direct-acting additional heater 30 a can be switched on, which quickly heats the contents to higher temperatures (Figure 9 of the drawing). If necessary, hot water can only be generated using the heat pump by switching over the three-way valve 19 take precedence. Another possibility is shown in Figure 10. By the arrangement of the condenser of the hot water tank the condenser of the buffer tank, hot water temperatures of up to 65 ° G can be achieved by utilizing the overheating heat.

The coefficient of performance of the heat pumps 1 is particularly high when temperature losses, which always occur in heat exchangers, can be avoided. The aim is therefore to use the evaporator directly, if possible without the interposition of another medium to be accommodated in the outside air as a heat exchanger, as the drawing Figure 6 already showed and how this particular figure represents.

In the warm season when no space heating is required, the work of the heat pump is determined by the heat demand of the hot water storage tank. The arrangement of Figure 10 has the advantage that the hot water preparation through heat recovery from the outside air can take place via evaporator 2 as well as from the latent storage via evaporator 4. When heat is obtained from the latent storage cold water is generated at the same time, which is used on hot summer days to cool the building via cold water circuit 8 a can be. Should more heat be generated when cooling the building in summer than is required for heating the domestic water, or in the hot water tank 3o and in the puf. fersüeicher 27 saved can be, then this arrangement according to Figure 1o enables the heat exchangers 35 a and 36 to dissipate the heat to the outside air. After the end of the cooling period, hot water is generated by extracting heat from the outside air. The supercooling heat is introduced into the latent heat exchanger.

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By means of a second outdoor heat exchanger 36 it can be achieved that on all days or hours of the day when the outdoor heat exchanger or other heat transfer media used are warmer than the content of the latent storage system, heat is withdrawn from this and through simple Circulation of a frost-resistant liquid to the latent storage 6 is supplied. The fin body of the outside air heat exchanger 36 can be incorporated into the lamellar body of the heat exchanger 2 be such that e.g. only the 1st, 3rd, 5th, 7th etc. tube of the lamellar body flows through the refrigerant of the heat pumps 1, while every 2nd, 4th, 6th, 8th etc. tube of the lamellar body from one frost-resistant liquid is flowing through it. Circulation pump 34 circulates the frost-resistant liquid. From the drawing Figure 1o is also (shown in dashed lines) it can be seen that instead of the convectively acting outside air heat exchanger 36, or in addition to this, a solar collector can be installed, which converts solar radiation directly into heat and it delivers this to the frost-resistant liquid circulated by the pump 34 for storage in the latent storage device 6. The system of obtaining environmental heat through heat exchangers 36 or 36 a can be expanded to include the frost-resistant liquid is rolled both through latent heat storage 6 and through buffer heat storage 27, such that at high latent storage temperatures e.g. from 40 ° C - 60 ° C at the beginning of the cold days, the frost-resistant liquid between the buffer tank 27 and the latent heat storage tank 6 is circulated.

In practice, the output of the heat pumps 1 is mostly divided between several heat pumps for reasons of better controllability and security against interference, etc. In order to keep the effort for control devices (three-way and solenoid valves, etc.) small, it is advantageous in such a case to provide a heat pump or a heat pump group 33 to transport heat from the latent heat store 6 to the buffer store 27, which operates at higher temperatures, as the drawing Figure 1o shows. The method according to the drawing FIG. 1o has the further advantage that the heat pump 1 can remain in operation ^{even at temperatures ^ <O 0 C.}

CL

^ <O ⁰

CL

Although its performance decreases at low outside temperatures, as shown in the drawing in FIG. 1, section DE, it still delivers

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the heating work represented by the trapezoid BCDE as an area, while heat pump 33 only does a work corresponding to the AED must provide the area of the triangle. The volume of the latent storage is reduced compared to the initially employed Bill to about a third because the triangle area AED makes up only a third of the total area ABCD, so that for an apartment has the aforementioned storage volume of

2 3 3

6.2 m by 2 m and for an 8-family house of 30 tn 10 m can be reduced, which is the volume of a cube with

the edge length of, / -j

^ yiO = 2.15 m

would correspond to.

This advantage is of course connected to _A the requirement on days with outside temperature ·
to operate power.

Days with outside temperatures νοηΠΡ_ <0 C a higher heat pump

3.

609839/0447

Claims (1)

Claims A method of space heating by means of heat pumps, characterized in that condensation heat from a heat pump system is introduced into a heat accumulator, from which the heat pumps extract the heat again in times of particularly high heat demand and raise it to the temperature level of the useful heat. Method according to claim 1, characterized in that in the Heat accumulator the undercooling and the excess heat of the refrigeration machine is introduced. Method according to Claims 1 and 2, characterized in that the summer heat exchanger is used by a special heat exchanger Heat extracted from the environment or obtained directly from the sun's rays without the interposition of a heat pump directly into the Memory is introduced. Method according to claims 1 and the following claims, characterized in that in a multi-storey house or comparable building, leather apartment assigned its own heat pumps that bring their excess and undercooling heat into a common storage for several apartments, from the In times of above-average heat demand, heat exclusively or in addition to heat extraction from the environment taken, fed via a distribution line to the evaporators of the heat pumps, by the heat pumps to the required level The temperature level is raised and made usable for room heating or hot water preparation. Method according to claim 1 and the following claims, thereby characterized in that the group of heat pumps, which extracts heat from the environment, is supplemented by a second group of heat pumps which, as soon as the heating system no longer receives enough heat, goes into operation and heat is removed in the long term Heat-storing storage tank transported into the heating system. Method according to claim 1 and the following claims, there- ' characterized in that the heat pumps bring their condensation heat into a separate buffer hot water tank, from which the hot water heating system is directly supplied with heat and from which the heat is drawn at the same time 609838/0447 " ² " to free the heat exchanger, which removes heat from the environment, of ice if necessary. 7. The method according to AnsOruch 1 and the following claims, characterized characterized in that depending on the heat demand of the object to be heated some or all of the condensation heat from the heat pump is fed to a hot water storage tank for domestic hot water will. 8. The method according to claim 1 and the following claims, characterized characterized in that the heat released during the air conditioning is used for heating the service water and when there is excess heat the heat is transferred to a long-term heat storage tank. 9. The method according to claim 1 and the following claims, characterized characterized in that the domestic hot water storage tank is a direct-acting electric or operated with other energy sources Includes auxiliary heating. 1o. Method according to claim 1 and the following claims, characterized characterized in that all of the processes described can be controlled automatically or manually. € 098 3 8/0447