EP2607810B1 - Method for operating a heat pump device - Google Patents

Description

The present invention relates to a method for operating a heat pump device according to the preamble of patent claim 1.

Due to their high thermal efficiency and energy efficiency, heat pump devices are used very economically and are used in large quantities.

The publication DE 10 2009 022 246 B4 discloses a hot water treatment device having a controller. This controller is provided in the lower storage area to ensure that water is quickly recharged when hot water is drawn. For this purpose, the temperature of the water in the storage tank is determined. This is done by a sensor. The sensor determines an integral temperature of the storage, so that conclusions can be drawn about the loading level of the storage. The charge level in turn can be used to regulate the hot water tank. This control takes place, for example, in an automatic mode. In the automatic mode, the charge level of the hot water tank is reduced to a lower threshold if there is no tap. However, if there is a tap, the charge level is increased to the previous value. The water is thus heated when the temperature falls below a constant threshold value. Depending on a subsequent or no dispensing process, the heating to an operating temperature or a temperature in the range above the threshold value takes place.

Furthermore describes for example the US 2005/01327332 A1 a method for controlling the start-up behavior of a heat pump water system. The system described is intended to prevent unintentional shutdowns and / or low operating efficiencies through a closed control loop. The document describes a method according to the preamble of claim 1.

It has been recognized that the service life and efficiency of a heat pump device or of its individual components are impaired by a relatively high clock frequency. For example, the frequency of switching the on and off is unfavorable Compressor and the associated conditions in the connected refrigeration circuit. When using older or sub-optimal storage tanks, falling below a threshold value or a minimum temperature can occur more often than with optimally insulated hot water tanks or optimal tank-heat pump constellations, whereby the life of the system is reduced in the case of sub-optimal constellations.

In the case of components that do not fit together optimally, for example a relatively small volume of water in the storage tank, the heat pump device often cycles. Or even with hot water storage tanks that are sub-optimally insulated, there are gradual heat losses. As a result of the heat losses in the prior art, the heating device or heat pump is actuated repeatedly within short phases, which may impair its service life.

The heat pump device known from the prior art always heats the water to the desired temperature in a normal operating state, starting from a constant switch-on value as the minimum temperature of the hot water supply. This results in frequent short operation with subsequent relatively short pauses in the case of an unfavorable fluid storage heat pump device constellation. This affects the life of the device or the overall system.

Each start and stop of the heat pump also has a negative effect on the coefficient of performance (COP) of the heat pump. Every time the heat pump is started, it takes a while for the compressor or refrigeration circuit to work optimally. In order to achieve the required long service life, it is therefore always a goal of the system design that the heat pump starts as little as possible and runs for a long time.

It is therefore an object of the present invention to optimize the operation of a heat pump device, in particular in the hot water preparation mode, in particular with regard to the service life and efficiency of the entire heat pump device and its components.

The solution to the above problem is achieved by a method for operating a heat pump device, in particular for hot water preparation or for hot water preparation. The fluid is, in particular, water which is stored in a fluid store, that is to say a hot water store. In a first method step, the temperature of the fluid is detected by a sensor device, in particular a temperature sensor. In a second process step, the fluid is heated to a desired temperature. As a result of the lowering of the temperature of the fluid to or below a minimum value, the fluid is heated to a value above the minimum value, in particular to the target temperature of preferably to 64 ° C.

According to the invention, the value of the minimum temperature is variable and is dependent on a period of time that has elapsed since the heating was previously carried out.

The task is thus solved by means of a variable starting temperature, which preferably starts with a default value of 40 ° C whenever the heat pump stops heating the domestic water and rises to the desired starting temperature. For this purpose, 56 ° C in particular are provided within a certain period, in particular 6 hours.

Irrespective of the respective component combination of the heat pump device, a variable temperature control method is provided that is optimized to the needs and properties of the respective combination. This leads in particular to the fact that the method can be used with optimally coordinated device components and with sub-optimally coordinated device components and enables the longest possible period between heating periods - while maintaining comfort requirements - whereby the functional reliability and the efficiency of all heat pump devices can be adjusted to a particular one Sets maximum value.

Thus, for example in a normal one or two-family house, activation of the heat pump device components for domestic water heating is normally sufficient every four to six hours, which results in a significantly reduced total number of actuations or a significant extension of the service life.

According to a further preferred embodiment of the present invention, the value of the minimum temperature is increased in constant time intervals from a predefinable minimum temperature. It is also conceivable that the time segments each comprise only one second or essentially one second or any other suitable time period. However, the time periods are preferably calculated, this is advantageous since the individual time periods can be optimally adapted to the properties of the components of the heat pump device.

According to a further preferred embodiment of the present invention, the increase takes place in predeterminable iteration steps, preferably calculated as a function of the respective heat pump device components, in particular by constant values. The values can be, for example, between 0.01 ° C and 1 ° C and is preferably substantially or exactly 0.1 ° C. This embodiment is advantageous because the minimum temperature can be raised to a target value for an optimal constellation for the entire system within a defined period of time. This means that the optimal minimum temperature can be set or set for different heat pump systems.

According to a further preferred embodiment of the present invention, the value of the minimum temperature is reset to the predetermined value when a desired temperature of the fluid is reached. It is conceivable that the time period that elapsed between the last reset is stored or output, as a result of which a change in the component behavior of the heat pump device can be determined on the basis of changing time periods.

This embodiment is advantageous since it provides an automatic self-adjustment / regulation by the heat pump device, thus avoiding human-machine interaction.

According to a further preferred embodiment of the present invention, the first time period begins to run when the reset is carried out and the increase takes place automatically. This embodiment is advantageous since a permanent and repetitive provision or initiation of the method according to the invention is also automatically realized.

According to a further preferred embodiment of the present invention, the length of the time segments is divided by the amount by dividing a predetermined maximum time period (in seconds) in which a minimum target temperature (in ° C.) can be reached starting from a minimum start temperature (in ° C.) the difference of x times, in particular 10 times, the minimum target temperature and x times, in particular 10 times, the minimum start temperature.

This embodiment is advantageous because a determination of the respective or optimal values can be carried out in a simple and thus resource-saving manner, in particular since the calculation has only a low level of complexity. Furthermore, the simple embodiment is always extremely reliable, inexpensive and easy to maintain.

According to a further preferred embodiment of the present invention, the predetermined period is between 3 and 9 hours, preferably between 4 and 8 Hours and particularly preferably essentially or exactly 6 hours. A period of 6 hours can, for example, correspond to a heating cycle of an optimal heat pump-fluid storage combination and thus enables an optimal efficiency setting.

According to a further preferred embodiment of the present invention, the minimum starting temperature is between 30 ° C. and 50 ° C. and preferably between 30 ° C. and 45 ° C. and particularly preferably essentially or exactly 40 ° C. A temperature of 40 ° C. is particularly preferred since at this temperature the fluid, in particular water, can still be used for a large number of uses. With 40 ° C warm water, for example, a heating device can still be operated or a shower process can be carried out.

According to a further preferred embodiment of the present invention, the minimum target temperature is a temperature between 50 ° C. and 70 ° C. and preferably a temperature between 50 ° C. and 60 ° C. and particularly preferably the minimum target temperature is essentially or exactly 56 ° C. This embodiment is advantageous with regard to the usual, economical design and operating range of a heat pump.

According to a further preferred embodiment of the present invention, the fluid is fed to the fluid reservoir in a feed device, such as, for example, a line, in particular a pipeline or a hose line, and the fluid is conducted from the fluid reservoir to a hot water consumer or a provision facility. A tap, a hot water pipe or a heating element, such as a radiator or a heating pipe, can be regarded as a hot water consumer, for example.

It is also conceivable that a heat pump device is designed such that it implements or executes a method according to the aforementioned features.

Fig. 1:

eine exemplarische Anlage zum Temperieren eines Fluides, die eine Vielzahl miteinander funktional verbundener Einrichtungen umfasst,

Fig. 2:

einen Heizverlauf einer aus dem Stand der Technik bekannten Anlage, und

Fig. 3:

einen erfindungsgemäßen Heizverlauf.

Further advantages, objectives and properties of the present invention are explained with reference to the attached drawings, in which heat pump devices or temperature profiles of heat pump devices are shown by way of example. Components of the heat pump device which in the figures at least essentially correspond in terms of their function can be identified with the same reference numerals, although these components do not have to be numbered or explained in all the figures. It shows:

Fig. 1:

an exemplary system for tempering a fluid, which comprises a large number of functionally connected devices,

Fig. 2:

a heating curve of a system known from the prior art, and

Fig. 3:

a heating curve according to the invention.

In Fig. 1 A structure of a device for heating 1 at least one fluid is shown. Such a device thus comprises, in addition to a receiving device 2, which is preferably a fluid storage or fluid tank, a sensor device 4 for detecting the temperature of the fluid, in particular in the tank, a heat transfer system 5, in particular a radiator, a heating device 6, in particular a heat pump 6, as well as further components arranged in the line, such as a supply device 16, in particular a tap or a tap, a valve device 18 and a compressor 20.

The water held in the tank 2 is preferably heated when the temperature in the tank 2 detected by the sensor device 4 is less than or equal to 56 ° C. The sensor device 4 is preferably arranged in the bottom region of the tank 2, it also being conceivable that several sensor devices 4 are arranged distributed in the tank, in particular at different distances from the bottom of the tank 2. In the case of several sensor devices 4, a control device (not shown) is preferred. provided that evaluates the recorded values, for example by averaging. The heating of the water preferably ends when the sensor device 4 reaches a target temperature 9 (cf. Fig. 3 ) of preferably> 56.5-57 ° C is detected or output. The above-mentioned temperatures can have higher or lower values depending on other recorded temperatures, in particular in a deviation range of 0.1-3 ° C.

The outer region of the tank 2 preferably comprises 20-300 l and particularly preferably 60-150 l and the heat pump 6 has a thermal output of preferably 1-20 kW and particularly preferably 5-14 kW. In the case of the interaction of a heat pump 6 that is too large for a specific tank 2, that is to say a heat pump 6 with an output power that is too high, the outer region of the tank 2 heats up very quickly, as a result of which the heat is not available in sufficient time to enter the tank To penetrate inside the tank 2. This is particularly problematic because the output of the heat pump 6 is not adjustable. The sensor device 4 The detected target temperature 9 is thus quickly reached and the heat pump 6 is stopped. It is also critical here that the exemplary heat pump 6 cannot work with temperatures higher than 57 ° C. inlet temperature and 64 ° C. outlet temperature, as a result of which the target temperature cannot be raised. Since there is initially a relatively high temperature difference between the inside of the tank 2 and the outer area of the tank 2, the temperature in the outer area drops rapidly, as a result of which the sensor device 4 detects a further drop below the critical temperature or the minimum temperature and consequently one further control of the heat pump 6 takes place. This is repeated several times within relatively short time intervals until the temperature is above the critical temperature or minimum temperature for a longer period.

In contrast, the functionality according to the invention makes it possible to provide a method or a device for heating 1 at least one fluid which, depending on the combination, i. H. with a specific heat pump 6 and a fluid reservoir 2, such as a process water tank (DHW tank) or heating water tank, as well as with only suboptimally matching components, in any case to heat the fluid at as far apart as possible times.

This means that in the event of an unfavorable component constellation, the temperatures of the fluid can be slightly lower at times, but the installer does not have to make any settings, since the variable start temperature solves the problem of the frequently occurring starts for hot water heating.

In Fig. 2 is an example of a heating curve 25 or the curve of an actual temperature 7 that results from the prior art in the case of less favorable component constellations. The abscissa 23 denotes the curve over time and the ordinate 24 denotes the temperature.

A minimum temperature is identified by reference numeral 8, when the temperature falls below or reaches the target temperature 9. Due to the relatively high temperature differences in the fluid area into which the heat is introduced during heating and in the fluid area into which the heat has to spread, a first relatively steep temperature drop area 21 is formed. The second temperature drop region 22, which is designed to be significantly flatter, only occurs when there is a very small temperature difference in the regions mentioned above. Since the heat pump device 1 stops when the target temperature 9 is reached, the heat is ready set, the heating curve 25 or the actual temperature 7 drops below the minimum temperature due to the large temperature difference, as a result of which further heating is initiated. This takes place frequently until the course of the actual temperature 7 corresponds to the course of the second temperature drop region 22.

In Fig. 3 A minimum temperature profile 8 is shown, which arises in a method according to the invention. The minimum temperature 8 changes over time from a minimum start temperature 10 to a minimum target temperature 12. The change can, as shown, be fluid or take place in stages.

With optimally coordinated components, the minimum temperature 8 therefore changes from the minimum start temperature 8 within the desired time or standard time 13 to the minimum target temperature.

In the case of suboptimally coordinated components, the courses of the actual temperature 7 and the minimum temperature 8 intersect or meet before the expiration of the standard time 13 (not shown). With a high consumption of tempered water, the first temperature drop region 21 meets the minimum temperature 8, as a result of which heating is initiated.

In the case of a lowering of the actual temperature 7 and / or low withdrawals of water only due to the temperature difference between the water area into which the heat spreads and the water area into which the heat is introduced, the second temperature drop area preferably coincides 22 with the curve of the minimum temperature 8. This therefore takes place as a function of the respective component constellation, as a result of which a response frequency which is adapted or reduced to the respective component constellation is set. The minimum temperature 8 is preferred when the actual temperature 7 corresponds to the target temperature 9, reset to the minimum start temperature 10.

REFERENCE SIGN LIST

1

Heating device

2nd

Reception facility

4th

Sensor device

5

Heat transfer system

6

Heater

7

Actual temperature

8th

Minimum temperature

9

Target temperature

10th

Minimum start temperature

12th

Minimum target temperature

13

Standard time

14

Feeding device

16

Provisioning facility

18th

Valve device

20

compressor

21

First temperature drop range

22

Second temperature drop range

23

abscissa

24th

ordinate

25th

Heating process

Claims (10)

1. Method for operating a heat pump apparatus (1), wherein a fluid is stored in a fluid store (2), at least one temperature sensor (4) detects the temperature of the fluid, a heating device (6) heats the fluid to a predefinable target temperature value, and, as a consequence of the temperature of the fluid being lowered to or below a minimum value, the fluid is heated to a value above the minimum value, wherein the value of the minimum temperature (8) is variable,
   characterized in that the value of the minimum temperature is dependent on a period of time which has passed since heating was previously realized.
2. Method for operating a heat pump apparatus (1) according to Claim 1,
   characterized in that, proceeding from a predefinable minimum temperature, the value of the minimum temperature (8) is increased at constant time intervals.
3. Method for operating a heat pump apparatus (1) according to Claim 2,
   characterized in that the increase, in particular by constant values, is realized in predefinable iteration steps.
4. Method for operating a heat pump apparatus (1) according to Claim 3,
   characterized in that, upon attainment of a target temperature of the fluid, the value of the minimum temperature (8) is reset to the predefined value.
5. Method for operating a heat pump apparatus (1) according to Claim 4,
   characterized in that, with the resetting, the first time interval starts to run and the increase is realized automatically.
6. Method for operating a heat pump apparatus (1) according to one of the preceding claims,
   characterized in that the length of the time intervals is determined by the division of a predetermined maximum period of time (in seconds), during which, proceeding from a minimum starting temperature (in °C) (10), a minimum target temperature (in °C) (12) is to be attained, by the magnitude of the difference between x times, in particular 10 times, the minimum target temperature (12) and x times the minimum starting temperature (10) .
7. Method for operating a heat pump apparatus (1) according to Claim 5,
   characterized in that the predetermined period of time amounts to between 3 and 9 hours, preferably between 4 and 8 hours, and particularly preferably 6 hours.
8. Method for operating a heat pump apparatus (1) according to Claim 5 or 6,
   characterized in that the minimum starting temperature (10) is a temperature between 30°C and 50°C, preferably between 35°C and 45°C, and particularly preferably 40°C.
9. Method for operating a heat pump apparatus (1) according to one of Claims 5, 6 and 7, characterized in that the minimum target temperature (12) is a temperature between 50°C and 70°C, preferably between 50°C and 60°C, and particularly preferably 56°C.
10. Method for operating a heat pump apparatus (1) according to one of the preceding claims, characterized in that the fluid is supplied in a supply device (14) to the fluid store (2), and the fluid is conducted in a provision device (16) from the fluid store (2) to a hot-water consumer (16).

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