DE102006024871B4 - A method of defrosting the evaporator of a heat pump heating system - Google Patents

Abstract

A method for defrosting the evaporator (4) of a heat pump heating system, which contains, in addition to the evaporator, at least one fan (5) which generates an air flow passing through the evaporator (4) and a compressor (1), the defrosting of the evaporator (4) at least in part by the fan (5) generating an airflow passing the evaporator (4) with the compressor (1) turned off, successive defrosting operations using different defrosting methods, with either a defrosting process using either a first defrosting method or is carried out using a second defrosting method, and wherein the first defrosting method consists in that the fan (5) generates a flow of air passing through the evaporator (4) when the compressor (1) is switched off, characterized in that it is dependent on the current need for heating the by the heat pump heating system to be heated medium depends on whether a defrost operation is performed using the first defrost method or using the second defrost method.

Description

The present invention relates to a method according to the preamble of patent claim 1.

Heat pump heating systems are used, for example, but by far not exclusively for heating heating water and / or service water. The energy required to heat the medium to be heated is taken, for example, from the air supplied to the heat pump heating system. Such heat pump heating systems are referred to as air / water heat pump heating systems.

The basic structure of such a heat pump heating system is in 1 illustrated.

That in the 1 The heat pump heating system shown is essentially formed by a flowed through by a refrigerant closed refrigerant circuit, which is a compressor 1 , a liquefier 2 , a thermostatic expansion valve 3 , and an evaporator 4 contains. In addition, a the evaporator 4 assigned fan 5 , which one the evaporator 4 generates passing air flow, as well as a control device controlling the above components 6 intended.

For the sake of completeness, it should already be pointed out at this point that only the components of the heat pump heating system of particular interest here are shown and described. Heat pump heating systems usually contain a whole range of other components, such as various temperature sensors and pressure switches, a condensate tray, a condensate tray heating, etc.

Through the compressor 1 the refrigerant circulating through the refrigerant circuit is compressed, this compression resulting in a correspondingly high heating of the refrigerant. The heated refrigerant (also called hot gas) comes from the compressor 1 to the liquefier 2 , The condenser 2 is a heat exchanger through which the hot gas and the medium to be heated by the heat pump heating system (heating water, service water, etc.) flows. In this heat exchanger, heating of the medium to be heated by the heat pump heating system takes place. Along with it, the refrigerant cools down. The refrigerant passes from the condenser 2 to the thermostatic expansion valve 3 , Through the expansion valve 3 the still pressurized refrigerant is expanded. As a result, refrigerant cools down even further. The expanded refrigerant passes from the expansion valve 3 continue to the evaporator 4 , The evaporator 4 is a heat exchanger through which the refrigerant flows, that of one from the fan 5 generated airflow is passed. The air is, for example, outside air drawn from outside the building and / or from inside the building sucked, for example, from a tumble dryer or a cooker generated hot air. Since the the evaporator 4 passing airflow is warmer than that at the evaporator 4 incoming refrigerant, the refrigerant is in the evaporator 4 heated by the air flowing past it. The refrigerant passes from the evaporator 4 continue to the compressor 1 in which it is compressed again.

The control device 6 controls the heat pump heating system. Among other things, it monitors the temperature of the medium to be heated and / or the heated medium and switches the heat pump heating system, more precisely the compressor 1 and the fan 5 the same depending on this and other parameters on and off. The control device 6 It also has a number of other features such as, but not limited to, turning off the compressor 1 and the fan 5 when the pressure in the hot gas leading part of the refrigeration cycle becomes too large.

During operation of the heat pump heating system forms on the evaporator 4 Ice. This is due to the fact that the evaporator 4 flowing refrigerant has a temperature below 0 ° C lying temperature. This is what happens on the evaporator 4 to form condensation, which immediately freezes.

Which is on the evaporator 4 As a result, the formation of ice blocks the heat exchange between the evaporator 4 passing air and the refrigerant. As the ice layer thickens, the heat exchange can even come to a standstill.

That's why it has to be on the evaporator 4 ice from time to time to be defrosted. This is often done using the so-called cycle reversal. The basic structure of a heat pump heating system, in which this is possible, is in 2A illustrated.

That in the 2A shown heat pump heating system contains all the components of the 1 shown heat pump heating system. Components denoted by the same reference numerals are the same or corresponding components. In addition, that contains in the 2A Heat pump heating system shown a four-way valve 7 , The four-way valve 7 has four ports, as in the 2A shown with the compressor 1 , the liquefier 2 , and the evaporator 4 are connected. Of the four ports, two are each internal Connecting routes interconnected. However, the internal connection paths are changeable. That is, it is adjustable, which connection of the four-way valve 7 with which other connection of the four-way valve 7 connected is. More precisely, by the control device 6 be adjusted, which connection of the four-way valve 7 with which other connection of the four-way valve 7 connected is.

There are two different settings, which are the first setting of the internal communication paths of the four-way valve 7 resulting connections between the individual components of the heat pump heating system in 2 B are illustrated, and wherein in the second setting of the internal communication paths of the four-way valve 7 resulting connections between the individual components of the heat pump heating system in 2C are illustrated.

The connections that occur at the first setting of the internal communication paths of the four-way valve 7 result (see 2 B) , are exactly the same connections as in the 1 shown heat pump heating system. That is, in the first setting of the four-way valve 7 is that in the 2A shown heat pump heating system in the heating mode.

The connections resulting in the second setting of the internal communication paths of the four-way valve 7 result (see 2C ), result in the result that a circulation reversal occurs. More precisely, it is here that this is the condenser 2 leaving refrigerant through the compressor 1 is compressed, and the compressed and accordingly hot refrigerant (the hot gas) in the evaporator 4 arrives. The high temperature of the evaporator 4 flowing through refrigerant has the consequence that on the evaporator 4 existing ice melts. That is, in the second setting of the internal communication paths of the four-way valve 7 is that in the 2A heat pump heating system shown in a defrost mode.

Such defrosting of the evaporator 4 has the disadvantage that in this case relatively much energy is consumed. First, will be electrical energy for the operation of the compressor 1 secondly, the refrigerant removes the medium to be heated in the condenser 2 Heat which must be returned to the refrigerant in a heating phase following the defrost phase. The latter is due to the fact that the refrigerant in the evaporator 2 and in the (with respect to the flow direction of the refrigerant) arranged behind the thermostatic expansion valve 3 strongly cools, and thus the condenser 2 flowing refrigerant is much colder than the medium to be heated by the heat pump heating system. This takes place in the liquefier 2 a cooling of the medium to be heated (and a heating of the refrigerant) instead. The renewed reheating of the medium to be heated after defrosting leads to a further consumption of electrical energy.

Another known method for defrosting the evaporator 4 is the so-called hot gas defrost. A heat pump heating system in which hot gas defrosting is possible is a heat pump heating system according to 1 in which, however, between the output of the compressor 1 and the entrance of the evaporator 4 an additional connection is provided. Such a heat pump heating system works during the heating phases like that in the 1 shown heat pump heating system; the additional connection between the output of the compressor 1 and the entrance of the evaporator 4 is blocked during the heating phases. In the defrosting phases, the refrigeration cycle is at one between the compressor 1 and the liquefier 2 lying point interrupted and the additional connection between the output of the compressor 1 and the entrance of the evaporator 4 open. This will get away from the compressor 1 produced hot gas as in the circulation reversal directly into the evaporator 4 and thaw it off. Such defrosting of the evaporator 4 however, also requires a lot of electrical energy.

The present invention is therefore based on the object to find a way by which the defrosting of the evaporator 4 required demand for electrical energy can be reduced.

This object is achieved by the method claimed in claim 1.

The method according to the invention proves to be advantageous in several respects. Firstly, much less energy is required for the operation of the fan than for the operation of the compressor, and secondly no or only negligibly small circulation of the refrigerant in the refrigerant circuit occurs when the compressor is switched off, so that the medium to be heated by the refrigerant no or only negligible little heat can be withdrawn and consequently no rewarming of the medium to be heated is required.

Advantageous developments of the invention are the dependent claims, the following description, and the figures removed.

• 1 den prinzipiellen Aufbau eines Wärmepumpenheizsystems,
• 2A den prinzipiellen Aufbau eines Wärmepumpenheizsystems, bei welchem bei Bedarf eine Kreislaufumkehr erfolgen kann,
• 2B die sich zwischen den Komponenten des in der 2A gezeigten Wärmepumpenheizsystems einstellenden Verbindungen, wenn sich das Wärmepumpenheizsystem in der Heiz-Betriebsart befindet,
• 2C die sich zwischen den Komponenten des in der 2A gezeigten Wärmepumpenheizsystems einstellenden Verbindungen, wenn sich das Wärmepumpenheizsystem in der Abtau-Betriebsart befindet, und
• 3 eine Veranschaulichung der Entscheidung, nach welcher Abtaumethode der im Wärmepumpenheizsystem vorhandene Verdampfer abgetaut wird.

The invention will be explained in more detail by means of embodiments with reference to the figures. Show it

• 1 the basic structure of a heat pump heating system,
• 2A the basic structure of a heat pump heating system in which, if necessary, a circulation can be reversed,
• 2 B which is between the components of in the 2A shown heat pump heating system adjusting connections when the heat pump heating system is in the heating mode,
• 2C which is between the components of in the 2A heat pump heating system adjusting connections when the heat pump heating system is in defrost mode, and
• 3 an illustration of the decision as to which defrosting method of existing in the heat pump heating evaporator is thawed.

The heat pump heating system described below is an air / water heat pump heating system. However, it should be noted at this point that the provision of the specific features of the described heat pump heating system can also prove advantageous in other heat pump heating systems.

The basic structure of the here presented Wärmepumpenheizsystems corresponds to the structure of in the 1 shown heat pump heating system or in the 2A shown heat pump heating system. However, the controller works 6 unlike the control devices provided in conventional heat pump heating systems. In particular, the defrosting of the evaporator takes place 4 unlike conventional heat pump heating systems.

The heat pump heating system presented here is characterized inter alia by the fact that the defrosting of the evaporator 4 at least partially done by the fan 5 with the compressor off 1 one the evaporator 4 produced passing airflow.

This allows the defrosting of the evaporator 4 to perform with a much lower demand for electrical energy than is the case with conventional heat pump heating systems.

Defrosting the evaporator 4 can be done solely by using the defrosting method presented here, ie only by the fact that the fan 5 with the compressor off 1 one the evaporator 4 passing air flow produced, or in combination with other defrosting methods such as the beginning with reference to the 2A to 2C described circulation reversal, and / or the above-described hot gas defrosting done.

"Defrosting the evaporator using only the defrosting method presented here" means that each defrost of the fan takes place solely in that the fan 5 with the compressor off 1 one the evaporator 4 produced passing airflow. In this case, the heat pump heating system in the 1 have shown construction, and would only have the operation of the control device 6 be modified. The modification of the control device 6 is that every time a defrost of the evaporator 4 necessary is the fan 5 switched on and the compressor 1 is turned off.

If and if so when defrosting the evaporator 4 is required is determined in the considered example, taking into account the length of time during which the heat pump heating system since the last defrost of the evaporator 4 in heating mode was. For example, it can be provided that a defrosting of the evaporator is performed after every 45 minutes heating time (heating pauses are not included). The mentioned time of 45 minutes can of course be longer or shorter.

• - der Anzahl und/oder der Länge der Pausen, während welcher sich das Wärmepumpenheizsystem seit der letzten Abtauung des Verdampfers 4 nicht im Heizbetrieb befand, und/oder
• - der Temperatur der das Wärmepumpenheizsystem umgebenden Luft, und/oder
• - der Temperatur der Luft, welche während des Heizbetriebes des Wärmepumpenheizsystems den Verdampfer 4 passiert, und/oder
• - der Verdampfertemperatur, und/oder
• - dem Kältemitteldruck im Verdampfer.

Determining whether and, if so, when defrosting the evaporator 4 is required, but can also be done additionally or alternatively depending on other or further parameters, for example, depending on

• - the number and / or length of breaks during which the heat pump heating system has been operating since the last defrost of the evaporator 4 not in heating mode, and / or
• the temperature of the air surrounding the heat pump heating system, and / or
• - The temperature of the air, which during the heating operation of the heat pump heating system, the evaporator 4 happens, and / or
• the evaporator temperature, and / or
• - the refrigerant pressure in the evaporator.

Taking into account individual, several or all of the mentioned parameters, the length of the defrost time can also be defined. As a defrosting time, however, it is also possible to use a fixed time independent of the aforementioned parameters. At present, it is preferred to defrost the evaporator 4 to stop when the evaporator temperature has reached a certain value.

• - dadurch, daß der Ventilator 5 bei ausgeschaltetem Verdichter 1 einen den Verdampfer 4 passierenden Luftstrom erzeugt, oder
• - durch die eingangs beschriebene Kreislaufumkehr.

In the above-mentioned defrosting of the evaporator 4 in which defrosting is done by a combination of different defrosting methods, consecutive defrosting operations can be performed using different defrosting methods. In the example considered, a respective defrosting process either takes place

• - in that the fan 5 with the compressor off 1 one the evaporator 4 produced passing air flow, or
• - By the circulation reversal described above.

However, it should be noted at this point that, instead of the circulation reversal, any other defrosting method, for example, the hot gas defrosting mentioned above, can be used. Furthermore, it is also possible to select the defrosting method to be used in each defrosting operation from more than two defrosting methods.

A heat pump heating system in which a respective defrosting either by the fact that the fan 5 with the compressor off 1 one the evaporator 4 produced passing air flow, or by the circulation reversal described above, can in the 2A have shown construction. However, the operation of the control device must 6 be modified. The modification of the control device 6 is that every time a defrost of the evaporator 4 is required, it is decided which defrosting method to defrost, and the compressor 1 , the ventilator 5 , and the four-way valve 7 be controlled as required to carry out the chosen defrosting method.

• - schaltet die Steuereinrichtung 6 den Ventilator 5 ein, und
• - schaltet die Steuereinrichtung 6 den Verdichter 1 aus.

In the first defrosting, ie for defrosting the evaporator 4 in that the fan 5 with the compressor off 1 one the evaporator 4 generates passing airflow,

• - Turns on the controller 6 the fan 5 one, and
• - Turns on the controller 6 the compressor 1 out.

• - steuert die Steuereinrichtung 6 das Vierwegeventil 7 so an, daß die Wärmepumpenheizsystem-Komponenten wie in der 2C gezeigt miteinander verbunden sind,
• - schaltet die Steuereinrichtung 6 den Verdichter 1 ein, und
• - schaltet die Steuereinrichtung 6 den Ventilator 5 aus.

In the second defrosting method, ie for defrosting the evaporator 4 by means of the circulation reversal

• - Controls the controller 6 the four-way valve 7 so that the heat pump heating system components as in the 2C are shown connected to each other,
• - Turns on the controller 6 the compressor 1 one, and
• - Turns on the controller 6 the fan 5 out.

The decision as to whether and when a defrosting of the evaporator is required, and the determination of the length of the defrost time is carried out as in the case described above, that each defrosting process is carried out solely by the fact that the fan 5 with the compressor off 1 one the evaporator 4 produced passing airflow.

According to which defrosting method a respective defrosting process is carried out, depends in the example considered on the temperature prevailing at the point from which the fan 5 the the evaporator 4 sucks in passing air. This temperature is in most cases the outside temperature of the building. Therefore, temperature of interest will be referred to as the outside temperature hereinafter for the sake of simplicity. As already mentioned, the evaporator can 4 Passing air, however, be sucked from a lying within the building body, so that the temperature to be determined is not necessarily the outside temperature.

For the selection of the defrosting method to be taken, two temperatures play a role in the example considered, namely a first temperature t1 and a second temperature t2 , where the first temperature t1 less than the second temperature t2 is. In the example considered, the first temperature lies t1 in the range between 1 ° C and 10 ° C, and is the second temperature t2 in the range between 5 ° C and 20 ° C. The temperatures t1 and t2 In principle, however, they can also be outside the specified ranges.

When the outside temperature is greater than the second temperature t2 is, the controller goes 6 assume that the evaporator 4 is not iced, and does not defrost the evaporator 4 by.

When the outside temperature is between the first temperature t1 and the second temperature t2 If there is a defrosting of the evaporator 4 after the first defrosting, ie by the fact that the fan 5 with the compressor off 1 one the evaporator 4 produced passing airflow.

When the outside temperature is less than the first temperature t1 is, there is a defrosting of the evaporator 4 after the second defrosting method, ie defrosting using the circulation reversal.

The described selection of the defrost method is in 3 shown.

The decision which defrosting method to defrost the evaporator 4 could be taken with additional consideration of the current need for heating of the medium to be heated. In particular, it could be provided to select a defrosting method with which the defrosting can be carried out as quickly as possible, if just a high demand for heating the medium to be heated, or to select a defrosting method, with which the defrost with the least possible consumption of electrical Energy can be carried out when there is no need or only a small need for heating of the medium to be heated. As a measure of the size of the need for heating of the medium to be heated, for example, the size of the difference between the current temperature of the medium to be heated and its target temperature can be used.

It could also be provided to make the decision on the defrosting method to be used, taking into account only the current need for heating the medium to be heated.

• - wenn der Bedarf an einer Erwärmung des zu erwärmenden Mediums während eines Abtauvorganges steigt, oder
• - wenn der Bedarf an einer Erwärmung des zu erwärmenden Mediums während eines Abtauvorganges sinkt.

In the example considered, no change in the defrosting method takes place within a respective defrosting process. However, it may prove advantageous if a change in the defrosting method can take place within a respective defrosting process. Such a change of the defrosting method could prove to be advantageous, for example, if a change in the need for heating of the medium to be heated occurs during defrosting, more precisely

• - When the need for heating of the medium to be heated during a defrosting increases, or
• - When the need for heating of the medium to be heated during a defrosting decreases.

In the former case, it could be envisaged to switch to a defrosting method by which the defrosting can be carried out more quickly than is the case when using the currently used defrosting method; in the second case, provision could be made for switching to a defrosting method which requires less electrical energy than is the case when using the currently used defrosting method.

Due to the outside temperature dependent use of different defrosting methods, the electrical energy consumption for the defrosting of the evaporator can be 4 at all costs to a minimum. Although requires the defrosting of the evaporator 4 using the circulation reversal relatively much electrical energy, but this defrosting method is so used only when it is absolutely necessary, ie when defrosting of the evaporator 4 in that the fan 5 with the compressor off 1 one the evaporator 4 produced passing air flow, either no longer possible or would be possible only with excessive expenditure of time and correspondingly high energy consumption.

It is even more favorable if use is made of the other defrosting possibility likewise described above, in which each defrosting of the evaporator takes place solely in that the fan 5 with the compressor off 1 one the evaporator 4 produced passing airflow. Such a heat pump heating system would not only have a particularly low energy consumption, but also a particularly simple structure (no four-way valve must be provided). However, such a heat pump heating system can be used only in areas where the outside temperature never becomes lower than or equal to 0 ° C.

LIST OF REFERENCE NUMBERS

1

compressor

2

condenser

3

thermostatic expansion valve

4

Evaporator

5

fan

6

control device

7

Four-way valve

Claims (12)

A method for defrosting the evaporator (4) of a heat pump heating system, which contains, in addition to the evaporator, at least one fan (5) which generates an air flow passing through the evaporator (4) and a compressor (1), the defrosting of the evaporator (4) at least in part by the fan (5) generating an airflow passing the evaporator (4) with the compressor (1) turned off, successive defrosting operations using different defrosting methods, with either a defrosting process using either a first defrosting method or is carried out using a second defrosting method, and wherein the first defrosting method consists in that the fan (5) generates a flow of air passing through the evaporator (4) when the compressor (1) is switched off, characterized in that it is dependent on the current need for heating the by the heat pump heating system to be heated medium depends on whether a defrost operation is performed using the first defrost method or using the second defrost method. A method for defrosting the evaporator (4) of a heat pump heating system, which contains, in addition to the evaporator, at least one fan (5) which generates an air flow passing through the evaporator (4) and a compressor (1), the defrosting of the evaporator (4) at least in part by the fan (5), with the compressor (1) turned off, generating an air stream passing through the evaporator (4), whereby successive defrosting operations can be carried out using different defrosting methods, characterized in that if, during a defrosting operation, there is a change the need for heating of the medium to be heated by the heat pump heating system occurs, the defrosting method is changed within the defrosting process in question. Method according to Claim 1 or 2 , characterized in that each defrosting of the evaporator (4) takes place solely by the fact that the fan (5) generates a flow of air passing through the evaporator (4) when the compressor (1) is switched off. Method according to Claim 2 Characterized in that a respective defrosting operation is performed selectively either by use of a first defrost method or using a second defrost method, wherein the first defrost method is that the fan (5) when the compressor (1) comprises the evaporator (4) passing Air stream generated. Method according to Claim 1 or Claim 4 characterized in that the second defrosting method consists of a circulation reversal of the refrigeration cycle contained in the heat pump heating system, in which the refrigeration cycle is so reconfigured during the defrosting phases that the flow direction of the refrigerant is opposite to that during the heating phases ¬stellenden flow direction of the refrigerant is, so that the compressed from the compressor (1) and accordingly strongly wär¬te refrigerant from the compressor (1) passes directly into the evaporator (4). Method according to Claim 1 or Claim 4 , characterized in that as a second defrosting method, a Heißgasabtauung is used, in which the heat pump heating system contained in the refrigeration cycle is reconfigured in the defrost phases so that it contains only the compressor (1) and the evaporator (4), so that the from the compressor (1) compressed and correspondingly strongly heated refrigerant from the compressor (1) passes directly into the evaporator (4). Method according to Claim 1 or Claim 4 characterized in that it depends on the temperature prevailing at the point from which the air passing through the evaporator (4) is sucked, whether a defrosting operation is carried out using the first defrosting method or using the second defrosting method. Method according to Claim 7 characterized in that a respective defrosting operation is performed using the first defrosting method when the temperature is greater than a first predetermined temperature, and performed using the second defrosting method when the temperature is less than the first predetermined temperature. Method according to Claim 8 characterized in that no defrosting operation is performed when the temperature is greater than a second predetermined temperature which is greater than the first predetermined temperature. Method according to Claim 8 , characterized in that the first predetermined temperature is in the range between 1 ° C and 10 ° C. Method according to Claim 9 , characterized in that the second predetermined temperature is in the range between 5 ° C and 20 ° C. Method according to Claim 1 or Claim 2 Characterized in that when a change in temperature occurs during a defrosting operation, which prevails at the location that the evaporator (4) passing air from which is sucked in, the defrost method is changed within the relevant defrosting.

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