DE3146902A1 - HEATING SYSTEM - Google Patents

Description

description

The invention relates to a heating system and in particular to an adsorption heat pump that is used in conjunction with a Melting heat storage is usable.

Various systems with solar radiation collectors and vapor compression heat pumps are already known, but they all have the disadvantage that their motor / compressor groups are relatively expensive. In principle, an adsorption heat pumps with a mixture of Methanol'und LiBr, ZnBr salts heat from -5 ⁰ C to + 6O ⁰ C with an efficiency (COP) in the region of 1.5. If such a heat pump has a suitable +60 C storage tank

would exhibit, they could be outside the electrical

Peak load times and could replace the boiler in existing hot water central heating systems. However, methanol is toxic, flammable, and is subject to dehydration by the above salts.

It is therefore the object of the invention to provide a simpler one
To create adsorption heat pumps that are proportionate
is cheap, which is not toxic for home use
Requires substances and those with an efficiency of
1.74 can be operated outside of peak load times
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According to the invention, the heating system has an evaporator housing for this purpose, an adsorbate and a heat exchanger. An adsorber includes an adsorbate and stands with the Evaporator in connection; a melt heat storage is connected to the adsorber and the evaporator. There are

Devices for supplying heat to the adsorbent in the adsorber, devices for extracting heat from the adsorber and facilities for obtaining heat from the melt heat storage are available. Furthermore, facilities are "Ό gen provided to moisten the heat exchanger housed in the evaporator with liquid and there are Means are available to condense the steam coming from the absorber to the melt heat storage

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The evaporator includes a heat exchanger. This heat exchanger is preferably a heat exchanger with a large surface area, for example an air-cooled heat exchanger or a heat exchanger, circulating speed in the liquid ^. In the latter case, the heated liquid is obtained from a solar radiation collector, for example.

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The solar radiation collector can take various forms and is, for example, a simple, unglazed receiver through which an ethylene glycol solution circulates. Typically, the temperature of the fluid, such as water or ethylene glycol solution, pulls out the heat from the solar radiation collector is relatively small, for example between -5 ° to +15 ⁰ C.

The solar energy is preferably supplied to a low-temperature heat store before it is transferred to the adsorbate accommodated in the evaporator, for example by heat exchange. A suitable low-temperature heat accumulator is described in the parallel GB patent application 8038284, which claims and describes a heat accumulator with * ° a tank, which has a liquid with a freezing point lower than O ⁰ C, in which at least one liquid-tight and heat-conducting container is submerged which includes a number of different substances each having freezing points between -5 C and +18 C and a latent heat of fusion greater than 125 kJ / kg and wherein a solar radiation collector is connected to the tank in such a way that heat received from the collector is on the liquid in the tank can be transferred and with means for pulling out the

Heat from the liquid are provided.

In any case, it is desirable to take heat from the heat exchanger housed in the evaporator temperatures as low as -8 C. It is . . therefore desirable that the adsorbate in the evaporator as well as elsewhere a liquid with a relatively is deep freezing. Suitable liquids include a solution of water and a suitable one Low vapor pressure anti-freezing agents, for example Calcium chloride or ethylene glycol.

An adsorber, which encloses an absorbent, is connected to the evaporator, for example via a line provided with a valve. There are also devices for supplying heat to the adsorbent in the adsorber , namely, for example, an electrical resistance heater, which is fed, for example, when the electrical network is under low load, at least outside of the peak load times.

The adsorber should be rechargeable at very low vapor pressures and therefore the preferred adsorbent / Adsorbate system 5A zeolite molecular sieve / water or in particular Y zeolite molecular sieve / water. It would be however, an activated charcoal / hydrogen ■■ iodite system or other zeolite molecular sieves with water,

for example, Y zeolite molecular sieves to use.

It is a device for extracting heat from the adsorber is provided and this is preferably a heat exchanger. Therefore, for example, a pipeline system, in the adsorbate, for example water, circulates and in connection with the melt heat storage device is provided with a section having turns, which is surrounded by the adsorbent, which is in the ad-

-IO sorber is housed. This pipeline system preferably contains a circulation pump. A preferred shape for a heat exchanger is in the parallel British patent application 80366901. This heat exchanger has a frame for supporting a connected pipeline system through which liquid can flow, as well as lines with permeable Walls that are at a distance from and close to the piping system, the scaffolding and the piping system consist of thermally conductive material. It is also a Means provided that can accommodate solids adjacent to the lines, but outside of them.

A melt heat accumulator is connected to the adsorber, for example through one provided with valves * Management. This heat storage comprises a container,

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ir. which contains one or more liquid-tight, thermally conductive containers, for example plastic or elastomer bags, each of which contains a substance with a high heat of fusion, ie over 150 joules / g. These containers are preferably made of flexible material in order to withstand the expansion and contraction of the substance housed therein. For this purpose, this material must be at a temperature of between 40 C and 80 ⁰ C melt. A particularly preferred sub "substance is stearic acid, which melts at 64 C and a latent heat of 199 Joules / g has. Other suitable substances are trichloroacetic acid (melting point 57.5 C, latent heat of 360 J / g), Tritriakontan (C _OO H_ _O) (melting point 71.1 ⁰ C, latent heat of 226 J / g) and palmitic acid (melting point 61.8 ⁰ C, heat of fusion 166 J / g). If the system is in operation, also in this adsorbate is the Heat storage tank surrounding the container.

There is a device for obtaining heat from the ^ ^u melt heat storage provided. This can be done by heat exchange, with a pipeline system in which liquid, for example water, circulates, being in a heat exchange relationship with the liquid, ie the adsorbate in the melted heat store. However, if the ^ adsorbate contains water, then the

The most moderate device for obtaining heat is the circulation of the adsorbate in the melt heat storage through a pipeline system that carries the heat to the consumer or to supplies the heat exchanger in the circuit having the consumer.

It "is" a device for humidifying the in the evaporator housed heat exchanger provided with water. This device is preferably a sprinkler, which is arranged in the evaporator above the heat exchanger. The liquid, which is an adsorbate, becomes preferably picked up from the bottom of the evaporator and returned to the sprinkler by a circulation pump. Another means of humidifying the heat exchanger involves the use of water absorbent coatings, which displace the evaporated water by capillary action.

It is also a facility in support of the

Condensation of steam provided, which reaches the melt heat storage device from the adsorber, and preferably to its upper area. This is expediently a circulation system with a circulation pump and a Sprinkler, with liquid from the bottom of the melt heat

Store back to the upper part of the melt heat store

where it exits through the sprinkler. The sprinkler is located on the top of the melt heat storage system near the point where Steam from the adsorber should preferably enter the melt heat storage. Preferably two valves are in This recirculation system is provided so that condensed adsorbate is delivered to the sprinkler in controlled amounts is feedable and a heat exchanger is for the feed designed from heat to the consumer, i.e. as a device for recovering heat from the melted heat storage. Not all of the heat generated needs to be stored in the melt heat storage, but it can be a Part can be used, for example, to provide hot water for the household.

There are also preferably devices for transferring liquids from the melt heat storage to the Evaporator provided. This preferably includes a pipeline provided with valves, which the melt heat

■■■■■■ - ■ - ■■

tank connects to the evaporator.

The system works as follows:

The system takes heat from an external source

the heat exchanger in the evaporator. This can be a solar radiation collector or a

ter heat exchanger. The heat supplied causes the adsorbate to evaporate from the evaporator and this vapor reaches the adsorber, in which it is adsorbed, whereby the heat of adsorption is transferred to the melted heat store

and then transferred to the consumer * This heat transfer is achieved by using the means to recover heat from the adsorber. Adsorbate, for example water, is conveyed through the heat exchanger into the adsorber and hot adsorbate

is delivered to the melting heat storage, where. it the Substance with a relatively high heat of fusion melts, for example stearic acid, which is stored in containers, e.g. Plastic bags, is housed. Part of the hot Adsorbate can circulate through the pipe system

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which supplies the heat to the consumer.

When the adsorber is fully loaded with the adsorbate, it can be discharged. This is achieved by by adding heat to the adsorbent, for example

by means of resistance heating, which is operated e.g. with night power, i.e. at times when there is no peak load operation prevails. The desorbed adsorbate vapor then reaches the melt heat storage, in which it is his gives off latent heat of condensation and thereby the substance

of relatively high heat of fusion, which melts in the

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liquid-tight containers housed in the heat accumulator is.

At the end of the discharge process (when no more heat is supplied), the temperature of the adsorbent is high and can be pushed back to a lower temperature by removing adsorbate from the heat storage tank the heat exchanger belonging to the adsorber is circulated intermittently. This process is facilitated by the

"Ό Controlled steam pressure in the melt heat storage and the In this way, excess inherent heat is transferred to the heat accumulator. If the desired deeper Temperature is reached, the adsorbate, which to the melt heat storage of the adsorber during the discharge process (the desorption), to the evaporator by opening the valve in the valved line be transferred, which connects the melt heat storage with the evaporator. This valve should be closed if the vapor pressure of the adsorbate in the melting

■ heat storage below the saturation vapor pressure of the adsorbate drops at the desired lower temperature. Heat can be obtained from the heat accumulator, inaem the liquid contained therein, i.e. the adsorbate, is circulated through the pipeline system, which generates the heat

^ supplies to the consumer. While the temperature is in

cools the heat accumulator, the melted substance, for example stearic acid, condenses in the containers and gives off its heat of condensation to the adsorbate, the

is housed in the melt heat storage. 5

The two steps of evaporating adsorbate from the evaporator and removing adsorbate from the adsorbent can of course also be reversed.

In practice, however, these steps apply arbitrarily often repeated for as long as heat has to be supplied to the consumer.

A preferred embodiment for the heating system is explained in more detail below with reference to a drawing:

The evaporator 10 contains water with a calcium chloride anti-freezing agent 15 as an adsorbate. Heat is supplied to the water 15 by the windings of a heat exchanger 36 with

increased surface area, which in turn has its own Heat from an air-circulated heat exchanger, not shown receives.

An adsorber 1 is connected to the evaporator 10 via a line

16 connected to a valve 3. The adsorber 1

includes a Y zeolite molecular sieve 17 and becomes heated by a resistance heater 2, which operated with night power, i.e. outside of peak load times will.

A line 18 is provided with a heat exchanger coil 11 in the zeolite 17 and with a pump 19. the Line 18 contains water and connects the upper end and to the other end of a melt heat accumulator 22.

At the upper end of the adsorber 17 is a line 21 connected, in which a valve 4 is located, which is also connected to the upper end of the melt heat accumulator 22 is. The melt heat storage 22 contains liquid

-j 5 adsorbate (water) 24 and a number of plastic bags 7. Each bag contains stearic acid (melting point 65 C, latent heat of fusion 199 joules / g). The floor The heat exchanger 22 is connected to a heat exchanger via a line 12 in which a pump 13 and a valve 14 are located 8 connected, which supplies heat to the consumer. A branch line 9 with a valve 5 connects the line 12 with a line 6 which connects the heat exchanger 8 with a sprinkler 20 in the upper part of the heat accumulator connects.

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A line 28 with a valve 29 connects the upper one Area of the heat accumulator 22 with the upper area of the evaporator 10. Finally, there is a circulation system provided for the evaporator 10, which has a line 25 with a pump 26, the bottom of the evaporator 10 connects to a sprinkler 27 which is arranged in the upper part of the evaporator 10.

In operation, the evaporator 10 absorbs heat from the heat exchanger 36, which has an increased surface area, but the temperature can be as low as -8 ° C. The heat exchanger 36 is humidified by the circulation system, which has the pump 26 and the sprinkler 27. The water evaporated at low temperature and pressure flows through valve 3 and is adsorbed by zeolite 17 in adsorber 1. In the preferred embodiment per 100 g of zeolite at 70 ⁰ C and a pressure can be adsorbed which corresponds to the vapor pressure of water at -5 C for up to 17 g water. The adsorption heat that is generated is transferred to the heat accumulator 22 via the heat exchanger 11 using the pump 19 and the line 18

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Valve 14 is circulated.

When the adsorber 1 is fully loaded, then can he will be discharged. To do this, the resistance heating 2 is switched on, for example with night power, valve 3 being closed and valve 4 being opened and water vapor being desorbed from zeolite 17 and is passed through the line 21 and the valve 4 to the top of the heat accumulator 22. Here the condenses

- | 0 water vapor and gives off its latent heat of condensation, whereby the stearic acid in the bags 7 is melted. During this discharge process, the pump 19 . stopped and the water in the heat exchanger 11 can to Heat accumulator 22 flow away. Water circulation through the heat accumulator 22 and jet condensation are through the Reached circulation system, which has the circulation pump 13, the lines 12, 9 and 16 and the sprinkler 20. the Valves 5 and 14 allow the flow of hot Ad.sqrbat (Water) by the pump 13 in a metered manner between the sprinkler 20 and the heat exchanger 8, which Supplies heat to the consumer.

At the saturation vapor pressure of water at 70 ° C. and at a temperature of 300 ^° C., the zeolite loses water until it contains about 4 g of water per 100 g, so that

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the working capacity is about 13 g / 100 g. The distant one Water vapor condenses in the heat accumulator 22 and melts the stearic acid in the bags 7, so that its heat of condensation is stored at 65 ° C. At the end of the discharge process, the adsorbent 17 has a temperature

of 300 ^° C. It is then ^{pressed again to 70 °} C. by repeatedly starting the pump 19, which is controlled by the vapor pressure in the heat storage device 22 and the excess self-heat in this way becomes the heat

-) 0 memory 22 transferred. When the temperature in the adsorber reaches 170 ^° C., the valve 29 is opened and the water that has been transferred from the adsorber 1 to the heat accumulator 22 can flow back to the evaporator 10, the valve 19 being closed when

-J5 the vapor pressure in the heat storage tank drops below the saturation vapor pressure of water at 70 ° C.

When the unloading process is completed, the loading of the adsorber 1 begins in the aforementioned manner again by allowing water to evaporate from the evaporator 10.

The latent heat of vaporization of water at 70 ° C is about 2.326 10 ⁶ J / kg (1000 BthU / lb), while the heat of adsorption is about 3.25 χ 10 J / kg (1400 BthU / lb). if

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a tolerance is allowed for the inherent heat collected by the zeolite between 70 C and 300 C, then the heat required to remove it is about 4.42 x 10 J / kg (1900 BthU / lb) and the expected efficiency is 2900: 1900 = 1.526, which is roughly the same as for a methanol absorption heat pump operating over the same temperature range. Each 45.4 kg of absorbent itself stores 0.424 χ 10 J / kg (18200 BthU) and this includes a further 2.06 χ 10 ⁴ kJ (19500 BthU) in the melt heat storage. This requires 103.2 kg (228 pounds) of stearic acid suitably encapsulated.

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Claims (18)

Claims Heating system, characterized by an evaporator which includes an adsorbate and a heat exchanger; by an adsorber connected to the evaporator and including an adsorbent; by a melt heat storage device which is connected to the adsorber and the evaporator; through a facility for supplying heat to the adsorbent in the Adsorber; means for extracting heat from the adsorber; through a facility to Extraction of heat from the melt heat storage; by a device for moistening the in the Evaporator enclosed heat exchanger and by a device to support the condensation of steam, which from the adsorber to the Melting heat storage arrives. 2. Plant according to claim 1, characterized in that a for transferring the heat to the evaporator air-circulated heat exchanger is provided. 3. Plant according to claim 1 or 2, characterized in that the adsorbent 4A and zeolite molecular sieve Adsorbate is water. 4. Plant according to one of claims 1 to 3, characterized in that the enclosed in the evaporator Adsorbate is an aqueous anti-freeze solution. 5. Installation according to one of claims 1 to 4, characterized in that the device for pulling out of heat from the adsorber is a heat exchanger. 6. Plant according to one of claims 1 to 5, characterized in that the melt heat storage container with stearic acid. ■ "· -"'" 3U6902 7. Plant according to one of claims 1 to 6, characterized in that the adsorbate is water and that the device for extracting heat from the melt heat storage is a pipeline system has through which the water circulates and heat to the consumer or one in a circle with delivers the heat exchanger lying to the consumer. 8. Plant according to one of claims 1 to 7, characterized in that the device for humidifying of the heat exchanger in the evaporator has a sprinkler above the heat exchanger is arranged, wherein the device is capable of adsorbate from the bottom of the evaporator to the sprinkler to overturn. 9. Plant according to one of claims 1 to 8, characterized characterized in that the means for assisting the condensation of steam emanating from the adsorber has a circulation pump and sprinkler capable of drawing liquid from the bottom of the To promote the melt heat accumulator back to the sprinkler, which is arranged in the upper area of the heat accumulator is. 10. Plant according to one of claims 1 to 9, characterized in that a device for transmitting of liquid from the melt heat storage to the evaporator is provided, 11. A method for obtaining heat, characterized in that (a) a heat source is used to To evaporate adsorbate from an evaporator, which is then from an adsorbent in an adsorber is absorbed and the latent heat of adsorption generated is conducted to a consumer, and that (b) a heat source is used to desorb the adsorbate from the absorbent in the adsorber, which then condenses in a melt heat storage and a substance with a relatively high latent heat of fusion melts, which subsequently solidifies, the resulting latent Melting heat that supplies heat for the consumer. 12. The method according to claim 11, characterized in that steps (a) and (b) are interchanged. 13. The method according to claim 11 or 12, characterized in that a heat source in step (a) Solar radiation collector is used. ... ... .. ... 3U6902 14. The method according to claim 11 or 12, characterized in that an air circulated as the heat source in step (a) Heat exchanger is used. 15. The method according to any one of claims 11 to 14, characterized in that as a heat source in step (b) electrical resistance heating is used. 16. The method according to any one of claims 11 to 15, characterized in that upon completion of the step (b) the adsorbent by intermittent circulation of adsorbate from the melt heat storage a heat exchanger belonging to the adsorber is cooled. 17. The method according to claim 16, characterized in that the adsorbate from the melt heat storage to the Evaporator is transferred when the adsorbent has been cooled. 18. The method according to claim 11, characterized in that that heat is obtained from the system according to one of claims 1 to 10.