RU2847379C1 - Method of centralised heat supply using a heat pump in water-air heating systems - Google Patents

Abstract

FIELD: thermal power engineering.

SUBSTANCE: the invention relates to thermal energy, in particular to centralised heat supply systems. The claimed method for centralised heat supply using a heat pump in water-air heating systems to increase the efficiency of the centralised heat supply system while reducing fuel consumption in heat supply sources includes heating network water in network heaters of heat supply installations, supplying hot water through the supply main pipeline to water-water heating heat exchangers installed in individual heating points, returning cooled water through the return main pipeline, heating devices, is distinguished by the fact that the temperature of the network water supplied to the heat exchangers is reduced to a temperature of 65-70 °° C, ensuring the operation of water heating using heating devices to cover only part of the heating load corresponding to heat losses through the building envelope, a vapour compression heat pump is used to heat the outside air entering the supply air duct of the air heating system, which provides the infiltration part of the heating load, the evaporator of which extracts heat energy from the return pipe of the water heating devices, the condenser is built into the supply air duct of the air heating system, heating the incoming air into the room through a recuperator, in which the removed air transfers heat to the incoming air.

EFFECT: the invention is designed to increase the efficiency of centralised heat supply systems by dividing the heating load in heating systems into two components.

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Description

The invention relates to thermal power engineering, specifically to centralized heating systems comprising three inextricably linked components: heat sources, transport communications, and space heating systems. Improving the efficiency of one component will improve the efficiency of the entire heating system. Residential and public buildings consume heat (heating load). ) to compensate for heat losses through the fences ( ) and heating of infiltrating (ventilation) air ( ) (Danilov O.L., Gariaev A.B., Yakovlev I.V. et al.; Energy saving in heat power engineering and heat technologies: textbook for universities edited by A.V. Klimenko. Moscow: MPEI Publishing House, 2010. 424 pp., p. 97).

(1)

Water is used as the primary heat transfer fluid in district heating systems, transferring thermal energy from the source to the heating units of buildings at flow and return pipe temperatures regulated by a 150/70 temperature schedule. In this case, a so-called hydronic heating system is implemented. Water enters the heating units of such a heating system at temperatures of 90-95°C. To reduce the network water temperature to these values, mixing devices—elevators or pumps—are installed in the central heating points of buildings. Water, passing through the heating units, completely transfers the heating load. air filling the interior space of heated rooms, maintaining the required temperature regime.

The disadvantages of central heating with water heating systems include:

1. Significant heat losses during transportation of water coolant;

2. Difficulty in regulating the heating load selection from the heating network, carried out according to the outside air temperature, while the regulated heating parameter is the indoor air temperature in the premises.

In forced-air heating systems, the air used for heating is a secondary heat transfer fluid, as it is heated in heaters by another, primary heat transfer fluid—hot water. In such heating systems, the air, heated to a temperature higher than the room temperature, gives off excess heat and, having cooled, returns to be heated again.

A space heating system using a heat pump is known, the condenser of which acts as an air heat exchanger, used as a heat source to heat the air supplied to the heated spaces (patent RU 2121114 C1, MKI ⁷ F24 D, BI 39, 1999). The heat pump's working fluid (freon) ensures full transfer of the heating load. the air passing through it.

The disadvantages of air heating systems, including heating systems using a heat pump (patent RU 2121114 C1, MKI ⁷ F24 D, BI 39, 1999) are due to the fact that the heat capacity of air is approximately four times lower than the heat capacity of the working fluid of the HP. Therefore, to transfer the required amount of heat, it is necessary to increase the air flow or its temperature by the same amount, bringing it to values of 120-150 °C. Such a temperature in domestic heating devices is unacceptable due to safety issues. Increasing the amount of supplied air leads to an increase in the noise of the unit and increases the intensity of air circulation in the heated rooms, which creates uncomfortable conditions for people and may violate sanitary standards (SN 2.2.4 / 2.1.8.562-96) for permissible sound pressure levels, sound levels, equivalent and maximum levels of penetrating noise in residential and public buildings and noise in residential areas.

The purpose of the invention is to increase the efficiency of a centralized heating system by reducing fuel consumption at heat sources. To achieve this goal, heat is provided in an amount equal to the heating load. divided into two heat flows: one of which, in an amount equal to the heat losses of the enclosing structures, transfers thermal energy to the heated air through the heating devices of the water heating system ( , the second heat flow in the amount of infiltration heating load transfers thermal energy to the outside air passing through the air heating heater built into the supply air duct of the ventilation system ( ).

The proposed hot water heating system is shown in the drawing.

The water section of the air-to-water heating system comprises a source heat exchanger 1, a supply 2, and a return 3 pipeline for transporting the coolant at a temperature of approximately 70°C from the source to the individual heating unit. In the water-to-water heat exchanger 4, heat is transferred to the water of the water heating system, which enters through supply pipes 5 into heating devices 6 at a temperature of ~65°C. The surface area of the heating devices is calculated based on the condition of heat transfer equal to the amount of heat loss through the enclosing surfaces. The temperature of the coolant at the outlet of the heating devices decreases to 45-55°C. Through discharge pipes 7, the spent water coolant is fed to the evaporator of the heat pump 8. Having given up heat, the water coolant returns to the water-to-water heat exchanger through the return pipe 9, and the circulation cycle is closed.

The working fluid of the heat pump (freon) after the evaporator 8 in a vapor state is compressed in the compressor 10 and with an increased temperature is supplied to the condenser of the heat pump 11, built into the supply air duct of the ventilation system 18, in which it transfers its heat to the outside air, which has undergone a pre-heating stage in the recuperator 13. The working fluid of the heat pump from the condenser 11 enters the throttle device 12, in which it lowers its pressure and temperature and returns to the evaporator 8. Then the operating cycle of the heat pump is repeated.

The air-to-air heating system is designed to heat outside air, the quantity of which is limited by air exchange standards. It enters the heated space through the supply air duct via supply fan 14, after undergoing two heating stages. In the first stage, the air is heated in heat exchanger 13 by extracting heat from air removed from the space via air intake 17, which is then exhausted by fan 16 to the outside via exhaust duct. In the second stage, the outside air, after passing through filter 15, enters heat pump condenser 11, which is a vapor-compression heat pump condenser. After passing through the condenser, the air raises its temperature to the temperature of the indoor air.

The heat pump acts as an individual heat source for the air-to-air heating system. The generated heat in the condenser of the heat pump 11 it consists of the thermal energy supplied to the evaporator 8 with water taken from the return pipeline of the water heating system 7 and electrical power of the compressor (10) .

(2)

The heat generated in the heat pump corresponds to the infiltration load.

(3)

The use of heat pumps in air heating systems improves the quality of heat supply regulation in heating systems, as the infiltration portion of the heating load is regulated based on a signal from the internal temperature sensor, taking into account all additional heat input into the heated space. The operation of the supply and exhaust ventilation system (air heating) is monitored by a set of temperature sensors.

Claims (1)

A method of centralized heat supply using a heat pump in hot water heating systems to increase the efficiency of a centralized heat supply system with a reduction in the consumption of fuel consumed in heat supply sources, including heating network water in network heaters of heating units (1), supplying hot water through a supply main pipeline (2) to water-to-water heating heat exchangers (4) installed in individual heating points, returning cooled water through a return main pipeline (3), heating devices (6), characterized in that the temperature of the network water supplied to the heat exchangers is reduced to a temperature of 65-70 ° C, ensuring the functioning of hot water heating using heating devices to cover only part of the heating load corresponding to heat losses through enclosing structures, for heating the outside air supplied through the supply air duct of the air heating system, providing the infiltration part of the heating load, a vapor compression heat pump is used, an evaporator (9) which takes thermal energy from the return pipeline of the water heating devices (6), the condenser (12) is built into the supply air duct of the air heating system, heating the incoming air into the room through the recuperator (13), in which the removed air gives off heat to the incoming air.