RU2656539C1 - Method for using solar energy for air conditioning systems - Google Patents

Abstract

FIELD: air conditioning systems.

SUBSTANCE: intended scope of use of a method for air conditioning based on a solar collector, engine with an external heat addition, a steam compression refrigeration unit and a thermal well for buildings with a variable thermal conditions, i.e., with thermal conditions, maintained not around the clock, but only during working hours in market and shopping complexes, sanatoriums and resorts; administrative buildings. During non-working hours, the temperature in the premises of this purpose can be maintained at a higher level during the warm period from a temperature set by regulatory documents. Heat of the solar collector through a heat carrier of a solar collector circuit is used to heat a working fluid in the engine with an external heat addition; engine with an external heat addition generates mechanical energy, which is used to drive directly the steam compression refrigeration unit that generates cold for the air conditioning system of a room. Heat carrier, which has given its heat in the engine, is returned to heat in the solar collector. Carrying away low-grade heat from the engine is transferred by means of heat-removable pipes to a heat-storing thermal well with a depth of 15–25 m, which will ensure the maximum efficiency of the engine.

EFFECT: method for obtaining cold in air conditioning systems based on solar energy in the warm period is proposed.

1 cl, 1 dwg

Description

The invention relates to methods for producing cold in air conditioning systems based on the use of solar energy in the warm period.

Known methods for producing cold in air conditioning systems [Plotnikov K.V., Alifanova A.I., Seminenko A.S. Air conditioning of buildings through solar energy. Modern high technology. No. 7, 2014.S. 59-61. Pleshka M.S. Climate control system of the building using solar energy. Diss. for the degree of Cand. tech. sciences. - M., 2005. - 288 p.].

The disadvantages of the known methods is that for this purpose an absorption heat pump is used, the heat transformation coefficient of which does not exceed 0.6.

There is also a method of producing cold in air conditioning systems using a steam compressor refrigeration machine [Svistunov V.M., Pushnyakov N.K. Heating, ventilation and air conditioning of agricultural facilities and housing and communal services. Textbook for high schools. St. Petersburg: Polytechnic, 2006 .-- 423 p. Ananyev V.A., Balueva L.P., Halperin A.D. and other ventilation and air conditioning systems. Theory and practice. Uch. manual - M .: "Euroclimate", publishing house "Arina", 2000. - 416 p.].

The disadvantage of this method is that an electric drive is used and double conversion of energy is necessary (thermal to electric, and then electric to cold, for which an electric motor is used).

Closest to the proposed method is a method of using solar energy with an external heat supply engine (Stirling engine) ["External heat supply engine". Patent No. 2105156 of June 23, 1995, RF], the implementation of which results in mechanical work. The Stirling engine is more efficient in converting solar radiation to electricity (31% efficiency) than most modern photovoltaic cells (commercially available elements with an efficiency of 14-18%, in the testing stage with an efficiency of 24-41%) and concentration-type solar power plants (parabolic gutters, tower structures - efficiency 16%).

The disadvantages of this method are:

- underutilization of the thermal potential of the solar collector in the summer;

- It is used only for generating electricity (an electric generator is needed).

The technical result of the proposed method is to increase the utilization of solar energy and reduce the arsenal of technical means for implementing the method (the absence of more expensive photovoltaic cells, an electric converter, an electric battery and an electric motor for driving a compressor of a steam compressor refrigeration machine). Thus, the use of solar energy according to the proposed method is more efficient than its use by obtaining electrical energy on photovoltaic panels, and then using it to drive a steam compressor refrigeration machine, because their efficiency, as noted earlier, is lower than the efficiency of the Stirling engine.

The specified technical result of the proposed method is achieved through the implementation of a set of features in which a new effect is achieved - an increase in the utilization of solar energy by 1.2 ÷ 2.1 times (taking into account the fact that the efficiency of the Sterling engine is more than 30% (and most modern photovoltaic elements have an efficiency of 14-18%), the heat transformation coefficient of the steam compressor refrigeration machine, depending on the temperature of the media (outdoor and indoor air) is 4 ÷ 7 (when using an absorption heat pump , the heat transfer coefficient does not exceed 0.6) and there is no double conversion of energy (thermal to electric using an electric generator, and then electric to cold, using an electric motor that provides the operation of a steam compressor refrigeration machine) and, accordingly, the arsenal of technical means is reduced (absence electric generator and electric motor).

The technical result is achieved due to the fact that in the method of using solar energy for air conditioning systems based on a solar collector, an engine with an external supply of heat, a thermal well with heat pipes, a vapor compressor refrigeration machine, the thermal energy generated by the solar collector is transmitted to the solar collector by the intermediate heat carrier an engine with an external supply of heat to generate mechanical energy, which is used to drive a steam compressor a cooling machine for generating cold for an indoor air conditioning system, and the waste heat from an engine with an external supply of heat through heat pipes is diverted to a thermal well.

During the warm season, the thermal energy generated by the solar collector is used in an engine with an external supply of heat to generate mechanical energy, which is used to drive a steam compressor refrigeration machine to generate cold for an indoor air conditioning system. The removed (low potential) heat from the engine with an external supply of heat is removed by means of heat pipes to a thermal well with a depth of 15-25 m, which has a high heat storage capacity and a relatively constant temperature, which will ensure maximum engine efficiency (at a depth of 15-25 m, the soil temperature is practically not depends on fluctuations in outdoor temperature).

The competitiveness of the proposed method is determined by a number of technical, economic and socio-environmental factors.

Technical factors

A distinctive feature of the proposed method based on the solar collector is:

a) the use of an engine with an external supply of heat, with the help of which they ensure the use of mechanical work received from the solar collector to drive a steam compressor refrigeration machine;

b) the use of a vapor-compressor refrigerating machine (PKHM), with the help of which they ensure the use of heat obtained from an engine with an external supply for air conditioning in the warm period.

Economic factors are determined by one-time capital costs and lower operating costs, due to which the return on capital costs is not more than 15 years.

Socio-environmental factors are characterized by the ability to provide cheaper cold air conditioning systems, as well as reducing atmospheric pollution.

In FIG. 1 shows a schematic diagram of a power plant for implementing a method of using solar energy for air conditioning systems.

The scheme includes the following elements: 1 - a solar collector with an intermediate coolant circuit (antifreeze); 2 - an engine with an external supply of heat; 3 - steam compressor refrigeration machine; 4 - heat pipes (with antifreeze) of the engine with an external supply of heat; 5 - thermal well, and heat fluxes are also shown: 6 - solar energy; 7 - coolant circuit of the solar collector; 8 - refrigerant of the air conditioning system of the room.

The method is as follows.

The heat of the solar collector 1 through the heat carrier (antifreeze) of the solar collector circuit is used to heat the working fluid in an engine with an external supply of heat 2; an engine with an external supply of heat generates mechanical energy, which is used directly to drive a steam compressor refrigeration machine 3, which generates cold for a room air conditioning system (during the warm season). Waste heat from an engine with an external supply of heat using heat-removing pipes filled with antifreeze is diverted to a thermal well 5 with a depth of 15-25 m, which has a high heat storage capacity and a relatively constant temperature, which will ensure maximum engine efficiency (at a depth of 15-25 m the temperature soil is almost independent of fluctuations in the temperature of the outside air). The coolant that has given up its heat in an engine with an external supply of heat returns to the solar collector for heating.

Technical characteristics of the effectiveness of the proposed method, as an example, are defined for a solar collector with an area of 100 m ² .

The maximum specific power of the solar collector at an outdoor temperature of 20 ° C can be taken q _max = 550 W / m ² . Technical characteristics of the module, with an area of 100 m ² , used by the proposed method: maximum thermal power of the solar collector - 55 kW; the average daily thermal capacity of the solar collector is summer (May - September) - 28.7 kW. The thermal power of the installation, working by the proposed method, for an air conditioning system in the warm period increases by 1.2-2.1 times.

Based on the average cold consumption for air conditioning of office premises 44 W / m ² [Ventilation and air conditioning systems. Theory and practice. Uch. Allowance. / Ananyev V.A., Balueva L.P., Halperin A.D., Gorodov A.K., Eremin M.Yu., Zvyagintseva S.M., Murashko V.P., Sedykh I.V .: M .: "Euroclimate", publishing house "Arina", 2000. - 416 p.], Air conditioning of premises with an area of 720-1370 m ^{2 is} possible.

The intended field of application of the method for air conditioning based on a solar collector, an engine with an external supply of heat, a vapor compressor refrigeration machine and a thermal well: for buildings with variable thermal conditions, i.e. with a thermal regime maintained not around the clock, but only during working hours (market and shopping complexes; sanatorium complexes; office buildings). During non-working hours, the temperature in the premises of this purpose can be maintained at a higher level from the temperature established by regulatory documents (building codes and regulations). At the same time, along with an increase in heat influx into the room during the day due to an increase in solar radiation, the capacity of the air conditioning system increases.

Thermal energy generated by the solar collector during the cold season can be used to heat water in a hot water supply system.

Claims (1)

The method of using solar energy for air conditioning systems based on a solar collector, an engine with an external heat supply, a thermal well with heat pipes, a steam compressor chiller, characterized in that the thermal energy generated by the solar collector is transmitted via an intermediate heat carrier of the solar collector to an engine with an external heat supply for the generation of mechanical energy, which is used to drive a steam compressor refrigeration machine to grow quipment cold for air conditioning of the premises, and the waste heat from the engine with an external supply of heat is withdrawn by teplosemnyh pipes in thermal wells.

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