DE102021001432A1 - Energy supply system for heating a heat sink with latent heat - Google Patents

Abstract

According to the invention, thermal containers serve as mobile thermal storage containers. Sensible heat and heat of crystallization of a latent heat storage medium transported therein enable a limited amount of heat to be supplied at varying temperatures and heating outputs. Since the required heat output of a heat sink can deviate from the heat supply of the heat container, the present invention relates to an energy supply system with a suitable adaptation. Circuitry of a heat pump according to the invention enables a deep discharge and/or long-lasting transfer temperatures above the phase transition temperature of the latent heat storage medium. In addition, a long-lasting, reliable supply of heat is realized by means of a superimposition circuit of two heat containers according to the invention.

Description

Background of the Invention

Heat pumps are used in thermal energy supply. In the prior art, they often extract the heat from open systems, for example the ground or the ambient air, in order to then supply it to a heating system.

In contrast, the present invention is directed to a closed system with heat sources in the form of heat containers that are discharged. According to the invention, latent heat storage media with a high storage capacity at at least one phase transition are preferably used for energy storage.

In 1 an exemplary discharge curve of a heat container is shown. The return temperature and the output power are plotted therein over the course of a discharge over time. Three areas of a discharge are clearly visible: an area of sensible heat SW, a latent heat area LW and an area of deep discharge TE. The heat is preferably emitted monotonically, ie no heat is supplied during a discharge process.

At the beginning of a discharge in the area of sensible heat SW, the temperature for crystallization of the melt is still too high and sensible heat is primarily supplied (time interval from 0 to 90 min 1 ). Crystallization is already setting in at certain points in the heating container, but a large part of the heat provided by the heating container does not (yet) consist of the associated heat of crystallization.

As soon as the heat container is unloaded into the latent heat area LW, the heat of crystallization keeps the temperature constant over a long period of time (time interval from 90 to 270 min 1 ). Most of the energy is provided in the latent heat range LW.

Only after the melt has crystallized throughout the entire container volume does the deep discharge TE follow, in which the temperature continues to fall, now also below the crystallization temperature (time interval from 270 to 390 min 1 ). The sensible heat and residual parts of the heat of crystallization are mainly decoupled here.

In one exemplary embodiment, 800 kWh of heat energy are stored in a heat container in the sensitive heat area SW, 1400 kWh in the latent heat area LW and 300 kWh in the area of deep discharge TE.

The discharge curve makes it clear that the heat available from the heat container is not constant. Heat output and transfer temperature vary. On the other hand, many heat sinks require constant and/or controllable heating power and/or transfer temperatures.

The object of the present invention is to stabilize the heat available from the heat container at the heat sink and/or to reliably cover the heat requirement.

character list

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying drawings. For simplicity, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily exaggerated or minimized for clarity. Furthermore, features can be simplified or reduced in number in order to better illustrate their structural principle.

• 1 zeigt ein Diagramm einer beispielhaften Entladekurve mit dem Bereich der sensiblen Wärme SW, dem Latentwärmebereich LW und den Bereich der Tiefenentladung TE;
• 2 zeigt ein Blockschaltbild einer reinen Speicherentladung ohne den Einsatz einer Wärmepumpe;
• 3 zeigt in einem Ausführungsbeispiel ein Blockschaltbild einer Installation mit einer Wärmepumpe WP in einem Betriebszustand der reinen Entladung gemäß 2, die Wärmepumpe WP ruht;
• 4 zeigt das Ausführungsbeispiel gemäß 3 in einem Betriebszustand, in dem durch die Wärmepumpe WP die Vorlauftemperatur an einer Übergabestation ÜS zur Wärmesenke angehoben wird;
• 5 zeigt das Ausführungsbeispiel der 3 in einem Betriebszustand, in dem die Übergabestation ÜS der Wärmesenke ausschließlich durch die Wärmepumpe WP versorgt wird, die Wärme aus dem Wärmecontainer C erwärmt ausschließlich einen Verdampfer V der Wärmepumpe WP;
• 6 zeigt eine Überlagerungsschaltung von zwei Wärmecontainern C1, C2 an einer Wärmesenke: Es erfolgt eine Vorwärmung durch einen Wärmecontainer C1 im Latentwärmebereich für einen Wärmecontainer C2 im sensiblen Bereich (C2 ≥ C1);
• 7 zeigt die Überlagerungsschaltung aus 6 nach einem Austausch des thermisch entleerten Wärmecontainers C1 durch einen befüllten Wärmecontainer C3: Über die Ventile W1, VV2 und UV1 werden die Flussrichtungen an den Seitenwechsel der Vorwärmung angepasst (C3 ≥ C2); und
• 8.zeigt eine hydraulische Kopplung zur Entladung von mobilen Wärmecontainern.

Reference numerals are used in the drawings that relate to the function of a structural feature, not to a specific place of use. For example, a pump P1 is a pump in each embodiment, but it may be used elsewhere. The precise purpose of use results from the context and/or is described for each exemplary embodiment.

• 1 shows a diagram of an exemplary discharge curve with the area of sensible heat SW, the area of latent heat LW and the area of deep discharge TE;
• 2 shows a block diagram of a pure storage discharge without the use of a heat pump;
• 3 shows in one embodiment a block diagram of an installation with a heat pump WP in an operating state of pure discharge according to FIG 2 , the heat pump WP rests;
• 4 shows the embodiment according to FIG 3 in an operating state in which the flow temperature at a transfer station ÜS to the heat sink is raised by the heat pump WP;
• 5 shows the embodiment of 3 in an operating state in which the transfer station ÜS the heat sink is supplied exclusively by the heat pump WP, the heat from the heat container C is heated exclusively an evaporator V of the heat pump WP;
• 6 shows a superimposed circuit of two heat containers C1, C2 in a heat sink: a heat container C1 in the latent heat range preheats a heat container C2 in the sensitive range (C2 ≥ C1);
• 7 shows the superimposed circuit 6 after replacing the thermally emptied heating container C1 with a filled heating container C3: The flow directions are adjusted to the change of sides of the preheating via the valves W1, VV2 and UV1 (C3 ≥ C2); and
• 8th .shows a hydraulic coupling for unloading mobile thermal containers.

Presentation of the invention

The purpose of the present invention is to reliably provide heat, which meets the heat requirements of a heat sink, by means of a suitable power supply system.

high temperature heat pump

In one exemplary embodiment, a heat pump, in particular a high-temperature heat pump (HTWP), is used to discharge at least one heat container. A thermal container according to the invention is a closed system with a limited amount of heat that is emitted monotonically.

The heat is preferably stored as latent heat at at least one phase transition of the container medium. Although the container medium also stores thermal energy (sensible heat), it supplies a large part of the energy as conversion enthalpy, which is converted isothermally at a phase transition. At the temperature for the phase transition, a great deal of heat is stored in the form of enthalpy of fusion and then given off again at a heat sink in the form of heat of crystallization.

By selecting the latent heat medium, the phase transition temperature can be adapted to the heating requirement within certain limits. The present invention optimizes this adaptation.

In one embodiment, the discharge is assisted by a heat pump, preferably a HTWP. Existing buildings can be heated in an environmentally friendly way without the need for ground collectors or groundwater tapping. Newly built quarters that do not have the appropriate space for heat generation can also be fed flexibly in this way.

The heat pump can be part of a mobile transfer point, for example installed in a 20-foot container. Attachments such as hydraulics, a controller and one or more buffer storage tanks can also be found in this mobile transfer point.

The mobile transfer point can be set up permanently or temporarily at a heat sink, for example a local heating supply point. The footprint can consist of reusable concrete slabs, for example. This mobile transfer point can be used, for example, to supply a local heating network as long as a planned local heating line has not yet been completed. The entire mobile supply, including the mobile transfer point, can then be dismantled and used at a new location.

By using a heat pump, the heat container can be unloaded more quickly, since the heat pump maintains or even increases the temperature gradient between the heat container and the delivery point. A deep emptying TE is thus reliably possible. A heat pump can also generate constant discharge temperatures at a transfer point, which simplifies integration into an existing heating system.

The starting point for using the heat pump is in 2 first a pure unloading process without support is outlined. The 35 to 95 °C warm heat exchange medium flows from a heat exchanger in the heat container C with the help of a pump P1 and transfers the heat energy to the heat sink, for example the building services HT, at a transfer station ÜS. The return flow then still has a temperature of around 30 to 50 °C. An adjustable maximum delivery temperature, for example about 70 °C, can be provided from the flow and return via a mixing valve MV1.

This pure discharging process can also be implemented in an arrangement with the heat pump, for example if the temperature in the area of the sensible heat SW is sufficiently high for the heat sink. 3 shows a corresponding embodiment: The heat pump WP rests. In the upper part of the 3 the pure discharging process can accordingly be omitted 2 recognize. To support the mass flow, an additional pump P4 can be present in the return.

An optional switchover valve UV4 enables the controlled discharge temperature for the transfer station ÜS by adding it from the return. The optional switching valve UV4 is in the 4 and 5 not shown again, but can also be provided there - then in a switching position that connects an intermediate store ZS with the mixing valve MV1.

4 shows the same arrangement during a discharge process with an active heat pump WP.

The heat pump WP can have an output of between 50 kW and 300 kW, for example 150 kW. It contains at least one evaporator VD, one expansion valve EV, one compressor V and one condenser K.

In this exemplary embodiment, a part of the flow is routed to the temporary store ZS by switching the valves MV1 and UV3, which is further heated by the heat pump WP. From the buffer store ZS, hot heat exchanger medium is added to the flow on the way to the transfer station ÜS via a mixing valve MV1, so that an adjustable transfer temperature above the flow temperature of the heat container C is possible.

The heat pump WP draws the heat from the return, which is coupled via a heat exchanger to an evaporator circuit of the heat pump WP. In this evaporator circuit, a pump P2 and a mixing valve MV2 ensure a regulated supply of heat to the heat pump WP.

The heat is delivered to the intermediate store ZS in a controlled manner at a condenser K of the heat pump WP using a pump P3 and a mixing valve MV3. Thus, the intermediate reservoir ZS, which has a volume of between 500 l and 5000 l, for example 3000 l, can heat up to preferably 70 to 85°C.

The same arrangement can be used in another embodiment according to FIG 5 be operated in such a way that the flow from the heat exchanger of the heat container only feeds the evaporator circuit of the heat pump. For this purpose, the inflow to the transfer station is diverted via valves UV1, UV2, UV3 and AV1 to the heat exchanger WT of the evaporator circuit. The transfer station ÜS is then supplied exclusively from the buffer store ZS.

On the one hand, this operating state is suitable for achieving a deep discharge of the thermal container, in which the thermal container has cooled down at the end, for example (e.g. only hand-warm), but the transfer temperature should remain high, for example at around 70 °C. A mixture of flow and intermediate storage would no longer reach this transfer temperature.

On the other hand, in this operating state, a heat sink can be supplied that has a high return temperature, which means that it requires a heat supply at a higher temperature than that provided by the heat storage medium. Here, too, a mixture of heat exchanger medium from the flow and intermediate storage would fall below the required transfer temperature.

In one exemplary embodiment, the operating states are combined with one another during a discharge process. For example, according to the operating state of pure discharge 3 be started (without using the heat pump WP) in which a sufficiently high temperature is available in the sensible heat SW area. In the latent heat range LW can then be in a first operating state with heat pump WP according to 4 be changed to at the end of the discharge process in a second operating state with heat pump according to 5 to realize the deep discharge TE.

Superimposed circuit with hydraulic coupling

In a further exemplary embodiment, a delivery temperature which is above the temperature of the phase transition is constantly achieved at the heat sink by a clever arrangement of the heat containers according to the invention. Although the proportion of sensible heat is only small compared to the latent heat, in this exemplary embodiment it is surprisingly sufficient to bring the amount of heat to be discharged almost entirely to an adjustable temperature above the crystallization temperature.

It can for this purpose 6 an arrangement can be selected consisting of two serially connected heat containers C1, C2, with a hydraulic coupling to a heat sink being set up in such a way that a first heat container C1, which has already been discharged into the latent heat region LW, preheats the heat exchanger medium to the temperature of the phase transition with latent heat and the second serially connected heat container C2, which is still in the sensible heat SW temperature range, further raises the temperature of the heat exchange medium to an adjustable higher temperature by sensible heat.

The hydraulic coupling can be set up in such a way that the first thermal container C1 is exchanged for a fully charged third thermal container C3 after it has been discharged can be, in which case the heat exchanger medium in the second heat container C2 in the latent heat range LW is then preheated to the phase transition temperature and the third serially connected mobile heat transport container, which is still charged above the latent heat range, further increases the temperature of the heat exchanger medium to the adjustable higher temperature using sensible heat.

A corresponding hydraulic coupling is in 6 shown. Two mobile heat transport containers C1 and C2 are available, in the example shown the mobile heat transport container C2 is warmer than C1 (C2 ≥ C1). Warm flows are denoted by gray arrows, with the solid gray arrows representing temperatures in the sensitive region above the latent region and the dashed gray arrows representing temperatures in the latent region. The black arrows relate to temperatures in the cold area, ie in the area of deep discharge TE (sensitive area below the latent area).

The return flow from the transfer station or the building services HT is first preheated in the heating container C1 via a switching valve UV1 and two distribution valves VV1 and VV2, and then raised to the sensitive area in the heating container C2. The stream from C2 is then mixed with another stream from C1 in a mixing chamber MK in such a way that the desired transfer temperature is reached.

As soon as the thermal container C2 has cooled down to the latent range and the thermal container C1 has been emptied, the thermal container C1 is replaced by a new fully loaded mobile thermal container C3 and the mentioned valves are switched so that the currents for the situation C3 ≥ C2 flow analogously to what is described above .

This new switching state is in 7 shown. Now the return from the transfer station or the building services HT is first preheated in the heating container C2, in order to then be raised to the sensitive area in the heating container C3. In the mixing chamber MK, the stream from C3 is then mixed with another stream from C2 in such a way that the desired transfer temperature is reached.

Once thermal container C3 has cooled to the latent range and thermal container C2 is emptied, thermal container C2 is replaced with a new fully charged mobile thermal container and the valves are re-adjusted 6 connected.

The hydraulic coupling ensures that mobile heat storage tanks can be exchanged alternately and that temperatures in the sensitive range can be offered over the longer term. In addition, the hydraulic coupling can provide a higher constant power compared to a single thermal container, since this results from the sum of the power outputs of the thermal containers C1 and C2 or C2 and C3. Since the valuable sensible heat only has to bridge the small temperature difference between the latent area of preheating and the desired transfer temperature, the two unloading processes coincide in time, although or precisely because there is significantly more latent heat available in the heat container for preheating than sensible heat in the heat container for further increase.

Temperature control with two heat flows

The following describes how, according to the invention, a mass flow with a defined intermediate temperature is produced from mass flows with different temperatures by mixing.

In a mixing chamber or at a mixing valve, for example, the heat from two heating containers should be brought together at a constant temperature T3. A corresponding arrangement is in 8th sketched. The two heat flows 1 and 2 are each moved by a pump P1 and P2, so that it is explained below how these pumps can be suitably regulated in order to constantly obtain the adjustable temperature T ₃ .

If two energy flows with the throughput ṁ ₁ and ṁ ₂ with the respective temperatures T ₁ and T ₂ are mixed together to form a mass flow ṁ ₃ with a temperature T ₃ , the resulting temperature T3 can be achieved by the following mixing ratio, where c _p is the specific heat capacity of the heat exchange medium: $$\begin{array}{l}\dot{Q}1+\dot{Q}2=\dot{Q}3\hfill \\ c_p\left({\dot{m}}_1{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1+{\dot{m}}_2{T}_2\right)=c_p{\dot{m}}_3{T}_3\hfill \\ {\dot{m}}_1{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1+{\dot{m}}_2{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_2={\dot{m}}_3{T}_3\hfill \\ {\dot{m}}_1{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1+{\dot{m}}_2{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=\left({\dot{m}}_1+{\dot{m}}_2\right)T_3\hfill \\ {\dot{m}}_1{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1+{\dot{m}}_2{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_2={\dot{m}}_1{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_3+{\dot{m}}_2{T}_3\hfill \\ {\dot{m}}_1\left({\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1-T_3\right)={\dot{m}}_2\left({\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_3-T_2\right)\hfill \\ \frac{{\dot{m}}_1}{{\dot{m}}_2}=\frac{{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_3-T_2}{{\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_1-{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="DE102021001432A1\_0009.png"\; state="\{\{state\}\}">T</figure-callout>}}_3}\hfill \end{array}$$

This mass flow ratio can in one embodiment by the. Power control of the pumps P1 and P2 for the mass flows ṁ ₁ and ṁ ₂ can be realized. In another out For example, a mixing valve or flow divider can produce this ratio. As long as one of the two mobile heat storage tanks is in the latent heat range and one in the sensible heat range, the mass flow ratio according to formula 1 ensures a constant temperature T3 at the transfer station.

In the event that neither of the two mobile heat transport containers is above the temperature T ₃ , the heat pump already described can raise one of the two energy flows to a temperature above T ₃ , preferably the warmer one. Alternatively, the mass flow ṁ ₃ resulting after mixing can also be increased to T ₃ .

Reference List

SW

area of sensible heat

Lw

latent heat range

TE

area of deep discharge

C, Cx

heat container

px

pump

ÜS

transfer station

HT

House technic

MVx

mixing valve

UVx

switching valve

AVx

shut-off valve

EV

expansion valve

WT

heat exchanger

WP

heat pump

vd

Evaporator

V

compressor

K

capacitor

ZS

cache

Wx

distribution valve

MK

mixing chamber

1, 2, 3

heat flow

tx

temperature

Claims (9)

Having energy supply system for heating a heat sink: - a heat pump, - a closed heat reservoir for monotonous heat emission, - a latent heat storage medium contained in the heat reservoir, - a transfer station to a heating system of the heat sink and - at least one buffer tank for heating by the heat pump. power supply system claim 1 , characterized in that the energy supply system has three circuits consisting of: - a direct supply of the transfer station from the heat reservoir, - a supply of the transfer station from the heat reservoir with admixture from the buffer storage, - a pure supply of the transfer station from the buffer storage. Energy supply system according to one of the preceding claims, characterized in that the heat pump is a high-temperature heat pump. Energy supply system for heating a heat sink, consisting of - Connection options for two closed thermal containers with monotonous heat emission to a serial circuit, - a hydraulic coupling of the thermal containers, and - a transfer station to the heat sink, with the heat containers each containing: - a latent heat storage medium for storing thermal energy and - a heat exchanger through which a heat exchanger medium flows via the connection options, the energy supply system being set up in such a way that a first heat container, which has already been discharged into the latent heat area, preheats the heat exchanger medium to the temperature of the phase transition with latent heat, and the second heat container is connected in series , which is still charged above the latent heat range, further increases the temperature of the heat exchange medium to an adjustable higher temperature by means of sensible heat. power supply system claim 4 characterized in that the energy supply system can be switched in such a way that the first mobile heat transport container can be replaced by a charged third mobile heat transport container after it has been discharged, in which case the heat exchanger medium in the second mobile heat transport container is then preheated to the phase transition temperature in the latent heat range and the third mobile heat transport container connected in series, which is still charged above the latent heat range, the temperature of the heat exchange medium by sensitive Heat further increases to the adjustable higher temperature. Energy supply system according to one of the preceding claims , characterized in that the energy supply system - is permanently installed or that the energy supply system - is mounted on a semi-trailer, a trailer or a truck or - is constructed as a container, in particular ISO container, or swap body, so that it Means of logistics can be transported from the heat sink to a further heat sink. Method for heating a heat sink with an energy supply system comprising: - a heat pump, - a closed heat reservoir for monotonous heat emission, - a latent heat storage medium contained in the heat reservoir, - a transfer station to a heating system of the heat sink, - at least one buffer storage tank for heating by the heat pump, with the method having three circuits consisting of: - a direct supply of the transfer station from the heat reservoir, - a supply of the transfer station from the heat reservoir with admixture from the buffer storage, - a pure supply of the transfer station from the buffer storage. Method for heating a heat sink with an energy supply system, consisting of - two thermal containers connected in series, - a latent heat storage medium contained in the heat containers, - Heat exchangers contained in the heat containers, through which a heat exchange medium flows, - a hydraulic coupling of the thermal containers, and - A transfer station to the heat sink, with the heat exchanger medium being preheated to the temperature of the phase transition with latent heat in a first heat container, which is already discharged into the latent heat area, and the temperature of the heat exchanger medium being preheated in a second serially connected heat container, which is still charged above the latent heat area is further raised to an adjustable higher temperature by sensible heat. procedure after claim 8 characterized in that the first mobile heat transport container is replaced by a charged third mobile heat transport container after it has been discharged, in which case the heat exchanger medium in the second mobile heat transport container is then preheated to the phase transition temperature in the latent heat range and the third serially connected mobile heat transport container, which is still charged above the latent heat range, further increases the temperature of the heat exchange medium to the adjustable higher temperature by means of sensible heat.

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