DE102013222677B4 - Heat transfer device, heat storage device and method for transferring and / or storing heat - Google Patents

Abstract

A heat transfer device (138) for transferring heat in a predetermined temperature range, comprising: - a first receiving device (140) for receiving a first medium, wherein the first medium is a medium whose specific heat capacity, especially at constant pressure, over the predetermined temperature range is substantially constant; - A second receiving device (142) for receiving a second medium, wherein the second medium is a medium whose specific heat capacity changes, in particular at a constant pressure, over the predetermined temperature range; A heat transfer region (144) in which heat from the first medium to the second medium and / or from the second medium to the first medium is transferable; A pressure changing device (148) for changing the pressure of the second medium during the transfer of heat from the second medium to the first medium, characterized in that the pressure changing device (148) comprises a plurality of valve devices (150) and / or throttle devices (152), by which the pressure of the second medium is lowered during the transfer of heat to the first medium and which are distributed along a flow path (168) of the second medium over the heat transfer region (144) away.

Description

The present invention relates to a heat transfer device for transferring heat from one medium to another medium.

Such heat transfer devices are used in particular in heat storage devices in which heat is transferred from a first medium, in particular a heat transfer medium, to a second medium, in particular a storage medium for storing heat.

Heat storage devices comprising such heat transfer devices find particular application in solar thermal power plants to store solar energy in the form of heat. The stored heat can then be used in particular for the operation of the power plant, if temporarily no or too little solar energy is available.

The DE 41 00 818 A1 discloses a method and apparatus for storing heat. In this case, a vaporizable heat transfer medium and a fusible storage medium are used to optimize heat transfer.

The present invention has for its object to provide a heat exchanger device by means of which heat can be transferred easily and efficiently from one medium to another medium.

This object is achieved by a heat exchanger device according to claim 1.

Characterized in that according to the invention a pressure change device is provided, by means of which the pressure of the second medium during the transfer of heat from the second medium to the first medium is changeable, preferably the specific heat capacity of the second medium can be adjusted during the heat transfer. In this way, heat can be transferred from the second medium to the first medium at a high efficiency.

The first medium is preferably a medium which is present in a solid and / or liquid state of matter over the entire predetermined temperature range. In particular, it can be provided that the first medium is a medium which is present in a liquid state of aggregation over the entire predetermined temperature range.

The second medium is preferably a medium which is gaseous and / or vaporous over the entire predetermined temperature range. In particular, the second medium is superheated steam over the entire predetermined temperature range.

The pressure change device comprises a plurality of valve devices and / or throttle devices, by means of which the pressure of the second medium during the transfer of heat to the first medium is lowered.

According to the invention, it is provided that the pressure change device comprises a plurality of valve devices and / or throttle devices, which are arranged distributed along a flow path of the second medium over the heat transfer area.

It may be favorable if the valve devices and / or throttle devices are arranged distributed along a flow path of the second medium over the heat transfer region in a substantially non-uniform manner.

The valve devices and / or throttle devices are, for example, distributed along the flow path of the second medium over the heat transfer region such that a distance between in each case two successive valve devices and / or throttle devices decreases with increasing flow path.

The valve devices and / or throttle devices thus preferably have a greater distance at a beginning (beginning) of the flow path of the second medium and a smaller distance towards the end of the flow path of the second medium in the heat transfer region.

The valve devices and / or throttle devices are preferably distributed along the flow path of the second medium across the heat transfer region such that the pressure of the second medium along the flow path decreases substantially linearly across the heat transfer region.

As an alternative to an uneven distribution of the valve devices and / or throttle devices, provision may be made for the valve devices and / or throttle devices to be distributed uniformly along a flow path of the second medium over the heat transfer region.

In one embodiment of the invention, it is provided that at least one Valve device and / or at least one throttle device, preferably all valve devices and / or throttle devices of the pressure change device, is designed as a direction-dependent pressure loss element.

A direction-dependent pressure loss element is in particular a pressure loss element, which generates a first pressure loss or pressure drop when flowing in a first direction and which causes a pressure loss or pressure drop different from the first pressure loss or pressure drop when flowing in a second direction opposite to the first direction.

In particular, it can be provided that at least one valve device and / or at least one throttle device is designed as a direction-dependent pressure loss element, which generates a larger pressure loss at a flow through the same for transmitting heat from the second medium to the first medium than during a flow through the same during a Transfer of heat from the first medium to the second medium.

The direction-dependent pressure loss element may for example comprise at least one movable flap element or be designed as at least one movable flap element.

A flap element is in particular an element which occupies different positions without an external, in particular manual, actuation in different directions of flow, thereby generating different flow resistances and different pressure losses.

It may be favorable if the pressure-changing device comprises a central pressure-changing device, by means of which a mean pressure of the second medium present in the heat-transfer region can be lowered globally during the transfer of heat to the first medium.

The central pressure change device thus forms, in particular, a central setting possibility for adjusting the mean pressure of the second medium over the entire heat transfer region.

A central pressure change device may be provided as an alternative or in addition to one or more valve devices and / or one or more throttle devices for locally lowering the pressure along the flow path in the heat transfer area.

In one embodiment of the invention can be provided that the heat transfer region comprises a plurality of switchable heat exchanger.

In particular, it can be provided that the heat transfer area is formed by a plurality of switchable heat exchanger.

The heat exchangers are in particular parallel and / or serially connectable.

For example, by parallel connection of heat exchangers targeted pressure loss can be generated.

It can be provided that the first medium is or comprises a sensitive heat storage material, for example a salt.

Furthermore, it can be provided that the second medium is or comprises water.

By way of example, the first medium is a sensible heat storage material, for example a salt, which is liquid over the entire predetermined temperature range. Furthermore, it can be provided that the first medium comprises a sensitive thermal heat storage material, for example salt, over the entire predetermined temperature range.

The second medium is preferably water vapor over the entire predetermined temperature range, in particular superheated steam. Furthermore, it can be provided that the second medium comprises water which is gaseous or vaporous over the entire predetermined temperature range.

The heat transfer device is particularly suitable for use in a heat storage device for storing heat.

The present invention therefore also relates to a heat storage device which comprises a heat transfer device according to the invention or several heat transfer device according to the invention.

The heat storage device according to the invention preferably has one or more of the features and / or advantages described in connection with the heat transfer device according to the invention.

A further object of the present invention is to provide a method by means of which heat can be transferred and / or stored easily and with high efficiency.

This object is achieved by a method according to claim 12.

The method according to the invention preferably has one or more of the features and / or advantages described in connection with the inventive heat exchanger device and / or the heat storage device according to the invention.

The pressure of the second medium is reduced during the transfer of heat from the second medium to the first medium such that the specific heat capacity of the second medium remains substantially constant, in particular during the cooling of the same over the predetermined temperature range.

Furthermore, it can be provided that the pressure and / or the temperature of the second medium are selected at a beginning of the heat transfer area such that the second medium is gaseous or vapor-shaped despite the targeted pressure change at one end of the heat transfer area.

The second medium is preferably supplied to the heat transfer area at a higher pressure than conventional heat transfer methods and / or at a higher temperature than conventional heat transfer methods, in particular so that the targeted pressure loss does not lead to condensation of the second medium.

Furthermore, the heat transfer device according to the invention, the heat storage device according to the invention and / or the method according to the invention for transferring and / or storing heat can have one or more of the following features and / or advantages:
The heat transfer device according to the invention and / or the heat storage device and / or the method according to the invention can be used in particular in solar thermal power plants. The present invention therefore also relates to a solar thermal power plant.

In a solar thermal power plant can be provided, for example, that by solar direct evaporation water as a heat transfer medium (in particular second medium) by means of a solar collector device (collector array) preheated, evaporated and overheated.

A heat storage device, in particular the heat storage device according to the invention, preferably also allows the heating, evaporation and superheating of the heat transfer medium, in particular water.

Since in the preheating and overheating the heat is sensitive, that is, under temperature increase, and in the case of evaporation latent, that is without temperature increase but with a phase change, is supplied, preferably adapted thereto storage systems are used.

For example, it can be provided that a latent heat storage device is provided as the evaporation device for evaporating the heat transfer medium.

For the heating (preheating) and / or overheating are preferably sensitive heat storage devices, in particular with Mehrtankflüssigsalzspeichern, for example on nitrate salt basis, provided.

In particular, when supplying heat to the superheating device by means of the heat transfer medium (second medium), there may be a disadvantage that the specific heat capacity of the heat transfer medium decreases with the temperature reduction occurring in the transfer of the heat. In particular, this can be disadvantageous if the specific heat capacity of a storage medium (in particular first medium) of the overheating device remains substantially constant during the heat transfer, in particular over the entire heat transfer area. The curve of the second medium is then significantly curved in the temperature-enthalpy diagram, while the curve of the first medium is at least approximately a straight line.

It can be seen that the maximum temperature, in particular steam temperature, at which a discharge, that is, heat transfer from the first medium to the second medium, is possible, is smaller than if the curve of the second medium in the temperature-enthalpy diagram also a straight line would be.

Since the temperature of the second medium, in particular the steam temperature, has a direct influence on the conversion efficiency of a power plant, in particular a solar thermal power plant, a deviation of the curve of the second medium in the temperature-enthalpy diagram from a curve formed as a straight line to an efficiency reduction , especially during a discharge lead.

By adjusting the specific heat capacity, in particular by changing the pressure, of the second medium during the transfer of heat from the second medium to the first Medium can be preferably counteracted the above-mentioned effect. In particular, this can preferably cause an increase in efficiency, in particular during the discharge.

Preferably, according to the invention, the steam temperature during the discharge of the storage to increase the efficiency can be brought closer to the steam temperature during the loading of the memory.

In particular, when the heat exchanger device comprises a plurality of heat exchangers, it can be provided that the heat exchangers are arranged and / or formed in cascade. In particular, in this case valve devices and / or throttle valves can be opened between the heat exchangers and / or other heat exchangers are switched on to achieve the desired pressure change during the transfer of heat from the second medium to the first medium.

In particular, when the pressure-changing device comprises a plurality of pressure-loss elements, in particular direction-dependent pressure-loss elements, it can be provided that these pressure-loss elements are distributed in a conduit, by means of which the second medium is materially separated through the first medium.

For example, it can be provided that second medium formed as water vapor is supplied to the heat transfer area at a pressure of at least about 100 bar, for example about 108 bar, and a temperature of at least about 300 ° C., for example about 316 ° C.

The first medium may be or include, for example, sodium nitrate and / or potassium nitrate.

Further preferred features and / or advantages of the invention are the subject of the following description and the drawings of exemplary embodiments.

In the drawings show:

1 a schematic representation of a solar thermal device in which a heat storage device is provided which comprises a heating device, an evaporation device and an overheating device for providing superheated steam, wherein the heat storage device is in a loading state;

2 one of the 1 corresponding schematic representation of the solar thermal device, wherein the heat storage device is in a discharge state;

3 a temperature-enthalpy diagram illustrating the heat transfer during the loading and unloading of the overheating device of the heat storage device;

4 a second embodiment of a solar thermal device in which a heat storage device is provided which comprises a heat transfer device for efficient heat transfer from a heat transfer medium to a storage medium;

5 one of the 3 corresponding temperature-enthalpy diagram for illustrating the heat transfer by means of the heat exchanger device 4 ;

6 an alternative embodiment of a heat transfer device, wherein a plurality of throttle elements are provided for reducing pressure along a flow path; and

7 an enlarged view of the area VII in 6 ,

Identical or functionally equivalent elements are provided with the same reference numerals in all figures.

One in the 1 to 3 illustrated first embodiment of a whole as 100 designated solar thermal device is used to absorb solar radiation to generate electrical energy.

To absorb the solar radiation includes the solar thermal device 100 a solar collector device 102 , by means of which solar radiation on a flow guide 104 is focusable to one in the flow guide 104 heated heat transfer medium, such as water to heat.

The solar collector device 102 thus serves in conjunction with the sun as a source of heat 106 for heating a heat transfer medium.

The solar thermal device 100 further includes a heat sink 108 to which the heated heat transfer medium can be supplied.

The heat sink 108 is for example a turbine device 110 for converting the thermal energy into kinetic energy, which is finally convertible into electrical energy, for example, by means of a generator device (not shown).

For driving the heat transfer medium in the flow guide 104 is a pump device 112 intended.

In particular, by means of the pump device 112 liquid water to the solar collector device 102 be supplied to evaporate the liquid water therein and overheat. The thus available superheated steam is then preferably by means of the pump device 112 to the turbine device 110 forwarded.

The solar thermal device described so far 100 is dependent on continuous solar radiation for continuous and reliable operation.

In particular, in cloudy skies or at night can thus by means of the solar thermal device 100 no electrical energy will be provided.

To at least partially compensate for this disadvantage, the solar thermal device includes 100 a heat storage device 114 , by means of which the solar collector device 102 Provided heat is at least partially stored for later delivery of the same.

The means of the heat storage device 114 stored thermal energy can then be used in particular for the generation of superheated steam, which for generating electrical energy of the turbine device 110 can be fed.

The heat storage device 114 includes a heating device 116 , a latent heat storage device 118 and an overheating device 120 ,

By means of the heating device 116 can the heating device 116 supplied liquid water to be heated.

By means of the latent heat storage device 118 The heated water can be evaporated. The latent heat storage device 118 thus forms an evaporation device 130 ,

By means of the overheating device 120 The generated steam can be overheated.

The heating device 116 , the latent heat storage device 118 and the overheating device 120 are with the flow guide 104 connected, so that the heating device 116 , the latent heat storage device 118 and the overheating device 120 in particular by means of the pump device 112 the heat transfer medium, in particular water, can be fed.

For storing the heat, the heat storage device comprises 114 multiple storage media.

A first storage medium is a latent heat storage medium, which in a storage container 122 the latent heat storage device 118 is arranged.

Another storage medium, for example, a sensitive heat storage medium, which in storage containers 122 a sensitive heat storage device 124 the heat storage device 114 is arranged.

The sensitive heat storage device 124 forms the heating device 116 and the overheating device 120 ,

To transfer heat from the heat transfer medium to the sensitive storage medium and / or to transfer heat from the sensitive storage medium to the heat transfer medium comprises the sensitive storage device 124 two heat exchangers 126 which with respect to a flow direction 128 the heat transfer medium in front of and behind the latent heat storage device 118 are arranged.

For example, in the in 1 illustrated loading state of the heat storage device 114 is the heat exchanger 126 , by means of which the overheating device 120 is formed, upstream of the latent heat storage device 118 arranged. The heat exchanger 126 , by means of which the heating device 116 is formed, is with respect to the flow direction 128 the heat transfer medium then downstream of the latent heat storage device 118 arranged.

In the in 2 illustrated discharge state of the heat storage device 114 follows with respect to the flow direction 128 the heat transfer medium, the latent heat storage device 118 on the heat exchanger 126 which the heating device 116 forms. On the latent heat storage device 118 then follows the heat exchanger 126 which is the overheating device 120 forms.

Like from the 1 and 2 is apparent, the latent heat storage device 118 one of the sensitive heat storage device 124 separate device.

In particular, independent storage containers 122 the latent heat storage device 118 and the sensitive heat storage device 124 intended.

The latent heat storage device 118 thus serves solely and the evaporation of the heat transfer medium and thus forms exclusively the evaporation device 130 the heat storage device 114 ,

The storage tanks 122 the sensitive heat storage device 124 are fluid effective with each other and with the heat exchangers 126 connected.

To provide different temperature levels for the heating or overheating of the heat transfer medium may be due to the use of multiple storage tanks 122 the sensitive storage medium with different temperature levels are kept.

The solar thermal device described above 100 works as follows:
By means of the pump device 112 the flow guide 104 becomes the solar collector device 102 Heat transfer medium, in particular liquid water fed.

In the solar collector device 102 the water is heated, evaporated and superheated using solar radiation. The heat transfer medium reaches, for example, a temperature of about 500 ° C and a pressure of about 100 bar.

In a next step, the heat transfer medium of the turbine device 110 supplied there and relaxed to convert the thermal energy into kinetic energy (mechanical energy).

The turbine device 110 finally drives a generator device (not shown) for generating electrical energy.

In the in 1 illustrated loading state of the heat storage device 114 may be a part of the solar collector device 102 heated heat transfer medium prior to delivery to the turbine device 110 be diverted.

The heated heat transfer medium, in particular the superheated steam, is then the heat exchanger 126 which is the overheating device 120 forms, then the evaporation device 130 forming latent heat storage device 118 and finally the heat exchanger 126 fed, which the heating device 116 forms.

The heated heat transfer medium releases heat to the sensible heat storage medium when it overheats 120 and the heating device 116 flows through.

Further, the heat transfer medium gives heat to the latent heat storage medium of the latent heat storage device 118 from.

By suitable supply of the sensitive heat storage medium to the storage containers 122 the sensitive heat storage device 124 For example, the sensible heat storage medium can store heat at different temperature levels to efficiently deliver the stored heat at a later time.

After the heat transfer medium has given off at least a large part of the heat contained therein, it can re-heat absorption of the solar collector device 102 be supplied.

The in 1 illustrated loading state of the heat storage device 114 is set especially when by means of the solar collector device 102 In strong sunlight, a large amount of heat is available and / or if only a small amount of electrical energy must be provided by the generator device with low load request.

The in the heat storage device 114 stored heat can thus be stored and provided at a later time.

To provide the in the heat storage device 114 stored heat becomes the heat storage device 114 in the in 2 shown discharged state.

In this discharge state is by means of the pump device 112 Heat transfer medium, in particular liquid water, to the heat storage device 114 fed.

The heat transfer medium first flows through the heating device 116 , then the evaporation device 130 and finally the overheating device 120 ,

By means of the heating device 116 the first liquid water is heated. By means of the evaporation device 130 the water is evaporated. By means of the overheating device 120 the steam obtained is overheated.

The superheated steam eventually becomes the turbine device 110 supplied to drive the generator device and generate electric power.

By means of the heat storage device 114 Thus, superheated steam for driving the generator device can be provided even if by means of the solar collector device 102 in the absence of sufficient sunlight, no heat or only a small amount of heat can be provided.

In the discharge of the heat storage device 114 become the heating device 116 and the overheating device 120 with heat from the sensitive heat storage medium of the sensitive heat storage device 124 supplied while the evaporator 130 Provides heat, which by means of the latent heat storage medium of the latent heat storage device 118 was saved.

3 shows a temperature-enthalpy diagram, which in particular shows that a load curve 132 and a discharge curve 134 of the heat transfer medium (second medium) are curved.

A memory curve 136 the storage medium (first medium), however, is a straight line.

The different curve of the load curve 132 and the discharge curve 134 on the one hand and the memory curve 136 on the other hand results from the different behavior of the specific heat capacity of the media in the heat transfer.

Since the heat transfer medium is essentially superheated steam when heat is applied to the overheating device 120 is transferred, changes in the cooling and heating, in particular overheating, the heat transfer medium whose specific heat capacity.

By contrast, the storage medium present, for example, as salt, in particular liquid salt, is liquid over the entire temperature range, which is provided for overheating the heat transfer medium, and has at least approximately a constant specific heat capacity over the entire predetermined temperature range.

Due to the different behavior of the media, there are losses in the efficiency of heat transfer.

In particular, a maximum steam temperature available during the discharge is relatively low.

One in the 4 and 5 illustrated second embodiment of a solar thermal device, in particular a heat storage device 114 , different from the one in the 1 to 3 illustrated first embodiment essentially in that the heat storage device 114 a heat transfer device 138 comprises, by means of which the heat transfer between the media, in particular between the heat transfer medium and the storage medium, is more efficient.

The heat transfer device 138 includes a first receiving device 140 for receiving a first medium, in particular of the storage medium, whose specific heat capacity over the temperature range during the overheating of the heat transfer medium is substantially constant.

Furthermore, the heat transfer device comprises 138 a second receiving device 142 for receiving a second medium, in particular the heat transfer medium, whose specific heat capacity over the predetermined temperature range, in particular in the overheating of the steam and / or upon cooling of the superheated steam changes.

The second recording device 142 is in particular the flow guide 104 ,

In a heat transfer area 144 the heat exchanger device 138 , which in particular by means of at least one heat exchanger 146 is formed, heat can be transferred from the storage medium to the heat transfer medium and / or from the heat transfer medium to the storage medium.

The heat transfer device 138 further comprises a pressure change device 148 by means of which a pressure of the heat transfer medium during the transfer of heat from the heat transfer medium to the storage medium changeable, in particular lowerable, is.

The pressure change device 148 In particular, it comprises a valve device 150 and / or a throttle device 152 for influencing, in particular for lowering, the pressure of the heat transfer medium.

The heat transfer device 138 includes in the in the 4 and 5 illustrated second embodiment, two heat exchangers 146 , which by means of the pressure change device 148 , in particular by means of the valve device 150 and / or by means of the throttle device 152 , are interconnected.

By means of the valve device 150 and / or by means of the throttle device 152 can thus a pressure drop between an upstream of the pressure change device 148 arranged heat exchanger 146 and a downstream of the pressure change device 148 arranged heat exchanger 146 specifically influenced, in particular controlled and / or regulated, be.

As in particular from a comparison of 5 and 3 emerges, by the targeted pressure influencing means of the pressure change device 148 by suitable pressure change of the heat transfer medium, the curved load curve 132 in a loading line 154 be changed.

This loading line 154 can then significantly better at the trained as a straight memory curve 136 be adjusted.

This allows a more efficient transfer of heat from the heat transfer medium to the storage medium.

Incidentally, the right in the 4 and 5 illustrated second embodiment of the solar thermal device 100 , in particular the heat storage device 114 , in terms of structure and function with in the 1 to 3 illustrated first embodiment, so that reference is made to the above description in this respect.

One in the 6 and 7 illustrated third embodiment of a solar thermal device 100 , in particular a heat storage device 114 or a heat transfer device 138 , different from the one in the 4 and 5 illustrated embodiment essentially in that the heat transfer device 138 several as pressure loss elements 158 trained valve devices 150 and / or throttle devices 152 includes, which in one or more lines 160 a heat exchanger 146 the heat exchanger device 138 are arranged.

The pressure loss elements 158 are in particular direction-dependent pressure loss elements 158 which cause different pressure losses depending on a direction of flow.

In the in the 6 and 7 illustrated embodiment is particularly provided that the directional pressure loss elements 158 in a flow through the same in a loading direction 162 cause a greater pressure loss than in a flow in a discharge direction 164 ,

The pressure loss elements 158 For example, flap elements 166 which is a directional pressure loss by folding or folding out into or out of a flow path 168 particularly strongly dependent on the direction.

In particular 6 it can be seen, are the pressure loss elements 158 along a flow path 168 arranged distributed.

The pressure loss elements 158 are in particular arranged so that a distance A between two adjacent pressure loss elements 158 when flowing through the line 160 in the loading direction 162 with increasing flow path 168 gets smaller.

For example, a distance A ₃ between two downstream pressure loss elements 158 smaller than the distances A ₁ and A ₂ between the other upstream pressure loss elements 158 ,

Through this distribution of the pressure loss elements 158 can be particularly accurate on the shape of the load curve 132 or loading line 154 Be influenced, in particular in order to obtain a linear as possible in the temperature-enthalpy diagram.

Incidentally, the right in the 6 and 7 illustrated third embodiment of the solar thermal device 100 , in particular the heat storage device 114 or the heat transfer device 138 , in terms of structure and function with in the 4 and 5 illustrated second embodiment, so that reference is made to the above description in this respect.

In particular, when the pressure of the heat transfer medium is deliberately reduced in the transfer of heat from the heat transfer medium to the storage medium, the heat transfer can be carried out particularly efficiently, in order ultimately to ensure efficient operation of a solar thermal device 100 to enable.

LIST OF REFERENCE NUMBERS

100

solar thermal device

102

Solar collector device

104

flow guidance

106

heat source

108

heat sink

110

turbine device

112

pump device

114

Heat storage device

116

heating apparatus

118

Latent heat storage device

120

overheating device

122

storage container

124

sensitive heat storage device

126

Heat exchanger

128

flow direction

130

Evaporation device

132

load curve

134

discharge curve

136

storage curve

138

Wärmeübertragervorrichtung

140

first receiving device

142

second receiving device

144

Heat transfer area

146

Heat exchanger

148

Pressure changing device

150

valve device

152

throttling device

154

Just load

158

Pressure loss element

160

management

162

loading direction

164

discharge direction

166

flap element

168

Flow path during loading

A ₁

distance

A ₂

distance

A ₃

distance

Claims (13)

Heat transfer device ( 138 ) for transferring heat in a predetermined temperature range, comprising: - a first receiving device ( 140 ) for receiving a first medium, wherein the first medium is a medium whose specific heat capacity, in particular at constant pressure, over the predetermined temperature range is substantially constant; A second receiving device ( 142 ) for receiving a second medium, wherein the second medium is a medium whose specific heat capacity changes, in particular at constant pressure, over the predetermined temperature range; A heat transfer area ( 144 in which heat is transferable from the first medium to the second medium and / or from the second medium to the first medium; A pressure change device ( 148 ) for changing the pressure of the second medium during the transfer of heat from the second medium to the first medium, characterized in that the pressure change device ( 148 ) a plurality of valve devices ( 150 ) and / or throttling devices ( 152 ) by means of which the pressure of the second medium during the transfer of heat to the first medium is lowered and which along a flow path ( 168 ) of the second medium via the heat transfer area ( 144 ) are distributed away. Heat transfer device ( 138 ) according to claim 1, characterized in that the valve devices ( 150 ) and / or throttling devices ( 152 ) along a flow path ( 168 ) of the second medium via the heat transfer area ( 144 ) are arranged distributed substantially unevenly. Heat transfer device ( 138 ) according to one of claims 1 or 2, characterized in that the valve devices ( 150 ) and / or throttling devices ( 152 ) along the flow path ( 168 ) of the second medium via the heat transfer area ( 144 ) are arranged distributed such that a distance (A ₁ , A ₂ , A ₃ ) between each two consecutive valve devices ( 150 ) and / or throttling devices ( 152 ) with increasing flow path ( 168 ) decreases. Heat transfer device ( 138 ) according to one of claims 1 to 3, characterized in that the valve devices ( 150 ) and / or throttling devices ( 152 ) along the flow path ( 168 ) of the second medium via the heat transfer area ( 144 ) are distributed such that the pressure of the second medium along the flow path ( 168 ) over the heat transfer area ( 144 ) decreases substantially linearly. Heat transfer device ( 138 ) according to claim 1, characterized in that the valve devices ( 150 ) and / or throttling devices ( 152 ) along a flow path ( 168 ) of the second medium via the heat transfer area ( 144 ) are arranged evenly distributed. Heat transfer device ( 138 ) according to one of claims 1 to 5, characterized in that at least one valve device ( 150 ) and / or at least one throttle device ( 152 ) as a directional pressure loss element ( 158 ) is trained. Heat transfer device ( 138 ) according to claim 6, characterized in that the direction-dependent pressure loss element ( 158 ) at least one movable flap element ( 166 ). Heat transfer device ( 138 ) according to one of claims 1 to 7, characterized in that the pressure change device ( 148 ) a central pressure change device ( 148 ) by means of which a in the heat transfer area ( 144 ) present medium pressure of the second medium during the transfer of heat to the first medium is globally lowered. Heat transfer device ( 138 ) according to one of claims 1 to 8, characterized that the heat transfer area ( 144 ) several switchable heat exchangers ( 146 ) Heat transfer device ( 138 ) according to one of claims 1 to 9, characterized in that the first medium is or comprises a sensitive heat storage material, for example a salt, and that the second medium is or comprises water. Heat storage device ( 114 ) comprising at least one heat transfer device ( 138 ) according to one of claims 1 to 10. Method for transferring and / or storing heat in a predetermined temperature range, in particular for overheating steam, comprising: - providing a first medium whose specific heat capacity is substantially constant over the predetermined temperature range; Providing a second medium whose specific heat capacity varies over the predetermined temperature range; Transferring heat from the second medium to the first medium in a heat transfer area ( 144 ); Changing the pressure of the second medium during the transfer of heat from the second medium to the first medium by means of a pressure change device ( 148 ), characterized in that the pressure of the second medium during the transfer of heat from the second medium to the first medium is reduced such that the specific heat capacity of the second medium remains substantially constant. A method according to claim 12, characterized in that the pressure and the temperature of the second medium at a beginning of the heat transfer area ( 144 ) are selected so that the second medium despite the targeted pressure change at one end of the heat transfer area ( 144 ) is gaseous or vaporous.

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