DE2515206A1 - Heat pump regulating system for improving economy - has two regulating valves responding to heat demand and air temperature - Google Patents

Abstract

The regulating arrangement for economical operation of heat pumps, ensures that the cold water supply temp., can be regulated during periods in which simultaneous or changeable cooling or heating is required for economical operation in relation to external air conditions. The waste heat exchanger (12) is controlled by a regulator valve (18) which is influenced by the evaporator (2) inlet temperature and also by the ambient air condition. Another valve (19) with low flow resistance is connected in parallel with the first valve in the heat recovery cycle and this additional valve is controlled by the heat demand. These two valves can be regulated by a computer in relation to ambient air enthalpy and the heat demand of the building.

Description

DR.-ING. BY KREISLER DR.-ING. BEAUTIFUL FOREST DR.-ING. TH. MEYER DR. FUES DIPL-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER WHHHHBMIB DIPL.-ING. SELTING

DR.-ING. EISHOLD 5 COLOGNE 1, DEICHMANNHAUS

7.4.1975 Sch / Sd

Brandi Ingenieure GmbH, 502 Frechen, Max-Planck-Str. 2-4

Control device for carrying out an economical operation of a heat pump device for air conditioning

The invention relates to a control device for carrying out an economical operation of heat pump systems when using heat sources with different, sometimes high temperatures, in particular from Waste heat sources, in which a water cooling system with evaporator and cold water circuit as well as with condenser and cooling water circuit including dry cooler is provided, and the evaporator a heat recovery circuit with waste heat heat exchanger and a heating water circuit is assigned to the condenser.

The availability of a heat source is an essential prerequisite for the operation of so-called heat pumps. Next to the amount of heat or waste heat, the temperature of the heat or waste heat has a decisive influence on the host

609843 / 05U

economic efficiency of heat pump systems. In particular this applies to compression heat pumps. To the To achieve economical operation, these systems must have the highest possible evaporation and the lowest possible Working condensing temperature. For this purpose, the heating water flow temperatures (outlet temperature from the condenser) of heat pumps sliding depending on the outside air temperature or enthalpy drove.

In general - especially when dew point coolers need to be supplied - they are necessary for air conditioning Cold water flow temperatures and thus also the evaporation temperature are kept constant. For the time, in which the outside air temperatures and thus the outside air humidity can reach high values, this becomes constant low cold water supply temperature with one more or less large tolerance is required. With medium and low enthalpy of the outside air, only a lower one Part or no part is required to dehumidify the air. The sensible heat to be dissipated is also included lower outside air conditions also lower. It is therefore often permissible during times with simultaneous or changing cooling and heating requirements in the interest an economical operation with a higher cold water flow temperature.

Is now intermittent during medium outside air conditions If the heating requirement is higher and the cooling requirement is temporarily higher, then on the one hand the heating water temperature must can be adjusted to a corresponding value depending on the outside air condition, on the other hand

609843 / 05U

However, the cold water circuit coupled with the heat recovery circuit should not be unnecessarily deep and none assume any high temperature. The latter would lead to the heat recovery and possibly the cold water circuit almost to the temperature of the waste heat source during the time of a small heating requirement would be heated up. If there is then a need for cooling, it would have to be stored in the heat recovery and cold water circuit The amount of heat must first be dissipated via the refrigeration system, which in addition to unavoidable power losses also has a causes impermissible time delay of the cooling effect.

Another reason for limiting the temperature in the heat recovery circuit results from the fact that when using reciprocating compressors either other devices to prevent the engine from being overloaded seized at high evaporation temperature or the drive motor itself is significantly oversized would have to.

The object of the invention is, in a device for heat recovery by means of heat pumps, of the type mentioned at the beginning Type the cold water flow temperature during the times when simultaneous or alternating cold and There are heating demand requirements for economic operation, as is the heating water temperature sliding depending on the outside air condition or to be able to drive in stages. The invention is distinguished by the type of control device mentioned at the beginning characterized in that the waste heat exchanger through one of the inlet temperature in the evaporator and optionally Regulating valve influenced by the outside air condition is, so that by means of the heat pump system an optimal Operating point can be driven.

609843/051 4

2ΤΤ57ΤΠ5 ""

With the help of such a control valve, which is located between the outlet side of the evaporator and the inlet side of the j Waste heat exchanger can be provided, it is possible to control the inlet temperature in the evaporator of the heat pump system to be able to adjust to a certain value that is optimal for cooling and heating operation until the with this temperature setting possible utilization of the waste heat source is exhausted compared to the pending heat demand to be generated by the condenser. It can During the transitional operation, the inlet temperature into the evaporator with the help of the regulated waste heat exchanger can be adjusted to a reasonably high value, for example to that provided in full-load cooling mode Cold water return temperature, so that on the one hand a high coefficient of performance of the heat pump operation is achieved on the other hand, large cooling losses and delays when switching to cooling mode are avoided.

During periods of excess heat, i.e. when the available heat is not completely consumed by the Heat pump is required to cover the heating demand, the operation with "optimal coefficient of performance" should be aimed for must, the utilization of this waste heat supply occurs with increasing heat demand and usually decreasing waste heat supply in the foreground in order to keep any additional heating that may be required as small as possible. It is then switch to operation with "maximum heat recovery". To this end, it is desirable that the the lowest permissible cold water temperature in the heat recovery circuit and the temperature difference at the same time between the inlet and outlet of the waste heat exchanger to be kept small in order to reduce the mean surface

6098A3 / 05U

lower the temperature of this heat exchanger as much as possible.

According to a further feature of the invention, there is a further valve for the control valve in the heat recovery circuit connected in parallel with low flow resistance. This further valve that allow an increased water flow is controlled depending on the heating demand in order to achieve the maximum possible with the heat pump system To be able to achieve heat gain. The lower limit of the cold water flow temperature is only limited by the safety requirements (risk of freezing, max. pressure ratio and possibly risk of icing of the Waste heat exchanger). In this way it is possible to use the available waste heat source as much as possible Extensive exploitation. The setpoint adjustment of the two valves is expedient to achieve one another an economical operation. The optimization can be done with the help of an electronic data processing system be improved.

The invention is based on a scheme shown in the drawing of a heat pump circuit with optimal and maximum heat recovery explained below.

The heat pump system has a heat pump with a grain; pressor 1, an evaporator 2 and a condenser j5, The evaporator is a cold water circuit 4 and the condenser j siger is assigned a heating water circuit 5. In addition, there is a heat recovery circuit 6 and 6 on the evaporator side a cooling water circuit 7 is provided on the condenser side,

60984 3/0 5 U

The circuit of the compression heat pump is designed so that it can operate during the hours of the year with high outside air conditions working as a refrigeration system that generates cold water for air conditioning. During the annual hours with simultaneous The heat absorbed in the air cooler 8 via the evaporator 2 with the aid of the Compressor 1 fed to the condenser 3. The amount of water circulated by the pump 9 distributes the warm water to the air heaters 10. If the amount of heat made available by the air heaters 10 is not taken, so they are discharged through a sprinkler cooler 11 to the outside air. On the other hand is the heating demand greater than the corresponding cooling requirement, the evaporator 2 must heat from the port air or another heat source are fed. For this purpose, the cold water circuit is coupled with a heat recovery circuit 6, in which a waste heat exchanger 12 and a pump 15 are located. The waste heat exchanger 12 is for example by means of fan 14 warm port air from the Building supplied.

In order to reduce the operating costs for the air conveyance, it is advantageous at the times when the waste heat exchanger 13 is not required to blow the air into the open via the bypass airway I5. This airway is to release via an air flap 16.

In order not to significantly worsen the heat transfers in the evaporator 2 and to increase the risk of the evaporator freezing ban, it is common to arrange a bypass line with control valve 17 in the cold water circuit. This ensures that a minimum amount of water is always passed through the evaporator, even during low-load operation. at in pure heating mode of the heat pump there is no cooling

609843/051 U

"" "■■" 25 'TS 2OF

promotion through the air cooler 8. The total in the heating water circuit required amount of heat for the air heater 10 must therefore by a correspondingly large amount of heat from the Waste heat flow can be obtained through the exchanger 12. To do this, through a correspondingly deep cooling of the waste heat flow to achieve, the control valve 18 and the parallel connected valve I9 are fully opened.

The control valve l8 is used during the simultaneous cooling and heating operation, the cold water inlet temperature into the evaporator is constant for both operating cases (excess cooling demand or excess heating demand) maintain a portable temperature value (optimal operation). With the help of the control valve 18, the inlet temperature into the evaporator 2 of the heat pump system on one certain optimal value for cooling and heating operation are regulated until the with this temperature setting possible utilization of the waste heat source in comparison to the upcoming one to be applied by the condenser 3 Heat demand is exhausted. By means of the parallel connected valve I9 with low flow resistance the water circulation in the heat recovery circuit can occur when both valves are opened 6 can be increased significantly so that operation with maximum heat recovery is possible. the Valves 18, I9 are advantageous with the help of a computer system depending on the outside air enthalpy and the cold and heat demand values of the building are regulated.

6 0 9 8 U 3/0 5 1 U

Claims (2)

A η s ρ rü ch e ι Control device for the implementation of an economical operation of heat pump systems when they are used of heat sources with different, intermittently high temperatures, in particular of waste heat sources, at the a water cooling system with evaporator and cold water circuit as well as with condenser and cooling water circuit including Dry cooler is provided and the evaporator a heat recovery circuit with waste heat -V / arm me from exchanger and a heating water circuit is assigned to the condenser, with a control valve for the evaporator is arranged in the bypass to the cold water circuit, characterized in that the waste heat exchanger (12) by one influenced by the inlet temperature into the evaporator (2) and possibly by the outside air condition Control valve (18) is adjustable. 2. Control device according to claim 1, characterized in that the control valve (18) in the heat recovery circuit (6) another valve (19) with low flow resistance is connected in parallel, and that the further valve (19) can be controlled depending on the heating requirement. J. Control device according to claim 1 and 2, characterized in that that the veritile (18,19) with the help of a computer system depending on the outside air enthalpy and the cooling and heating demand values of the building can be regulated. I. 609843 / 05U