CC BY
2
DOI 10.46566/2225-1545_2020_77_146 UDK 004.02:004.5:004.9
Mirzayorova S. U.
2nd year master's degree in industrial thermal energy
Faculty of Energy Karshi Institute of Engineering Economics
INCREASING THE EFFICIENCY OF NATURAL COLD ACCUMULATION SYSTEM
Annotation: Accumulation of Natural Cold is (heat) - the use of the phenomenon of heat absorption (release) during the phase transitions of a substance. A classic example of a cold battery is the use of so-called. In the pre-industrial period, "glaciers " preceded the emergence of industrial and domestic refrigerators. In the winter, ice was stored, which was stored in a heat-insulated place (cellar, basement), which later allowed food to be stored throughout the summer, gradually melting and absorbing the incoming heat. Nowadays, cold accumulators are used in household refrigerators to mitigate the temperature rise that occurs during the automatic operation of the refrigerator and, most importantly, to ensure the preservation offood in the event of a power outage.
Keywords: Natural cold, batteries, seasonal cold, geographical location, environment, compressor, active cooling.
Cold accumulators are usually flat plastic containers filled with an aqueous solution of salt (usually potassium chloride). In Stinol refrigerators, the cold batteries are equipped with a refrigerator at the same time as usual. Cold batteries are sold in stores and separately, but you can do it easier and cheaper - make them yourself. To do this, you need a cool solution of plastic bits and sodium chloride in water. Even better, if the chlorine is potassium, it will keep better in the cold because it freezes at lower temperatures. Cold batteries can help you seriously if the power goes out frequently in your area or the voltage drops so low in the evening that your refrigerator doesn't work (a common occurrence in rural areas). If your refrigerator has a very powerful compressor rustle, a cold battery will help very well - this is often the case with older Soviet refrigerators with a DHK compressor, and the XKV-6 also ruthlessly rustles. If you don't have the money to buy a new refrigerator or replace a compressor, a home-made cold battery will help you. True, it takes up space in your fridge, but it allows you to live more comfortably with your fridge. You can turn on the fridge with a cold battery in the fridge when you go to work or the workplace, and when you arrive, or even more sleepy, you can safely turn off the fridge without worrying about food safety - a cold battery does it for you does. Most importantly, don't forget to turn on the fridge again in the morning, otherwise the cold in the cold battery will run out and
the food will deteriorate. There is one more "but" - the salt in a cold battery is very corrosive.
One of the traditional ways to reduce energy consumption is to use seasonal cold storage, which takes advantage of the geographical location of the country, which allows cold to accumulate during the winter, i.e. November, December, January, February and March due to lower ambient temperatures. . Consumption of electricity and refrigeration, which is harmful to the environment, is reduced. This article describes the size of a refrigeration unit equipped with a refrigerator and dry-cooled chargers. The estimated cost of using the device, as well as the assembly time of the components, was estimated. Seasonal cold storage battery has a number of economic and environmental advantages. The seasonal tank design is a prototype of a refrigeration machine that is smaller than a traditional tank selected for maximum power consumption per hour. This means that the actual device must be several times larger than the device used in the project. By choosing a small refrigeration unit called R-410A and less refrigerant (mainly CFC), the environment is protected from contamination with life-threatening substances.
The efficiency of the existing cooling accumulator depends on the intensity of heat exchange and the amount of energy consumption: the higher the first, the lower the second, the more efficient equipment is used. In large industrial plants operating powerful refrigeration units, even a relatively small increase in the energy efficiency of refrigeration units provides significant economic benefits. Even in the calculation stage of cooling systems, when a specific cooling supply scheme is selected for the enterprise, equipment is selected and its operating mode is determined, mechanisms to reduce the energy consumption of the system are provided.
One of the most effective ways to reduce the cost of operating and maintaining industrial refrigeration plants for businesses in temperate climates, where the low-temperature cold season lasts longer, is to use natural cold. According to recalculations, the use of naturally cold accumulators is appropriate for both medium-temperature cold devices and low-temperature units; Regardless of the method, the use of low ambient temperature reduces the energy consumption of the refrigeration unit, significantly reduces the load on the compressor units, and also increases the environmental friendliness of the operation of the refrigeration equipment. By using the accumulation of natural cold, it is possible to significantly reduce the service life of compressors, reduce the maintenance costs of screw compressors and reciprocating units, as well as the cooling system as a whole. The calculation when choosing a refrigeration machine (chiller) is based on the maximum temperature of the summer period, as high condensing temperatures and difficult operating conditions of the equipment result in high energy consumption. One of the opportunities to increase the efficiency of a refrigeration refrigerator is the ability to create artificial cooling at low outdoor temperatures using the natural circulation of this refrigerator. The
circulation of the refrigerant is done at the expense of part of the heat energy, which is taken from the cooled body without supplying mechanical energy to the compressor due to the location of the condenser and evaporator. The compressor discharge and suction lines are connected to the shut-off valve by a bypass line, while the air-cooled condenser is located above the evaporator. Then, when the outside air temperature drops below the boiling point of the refrigerator to 7 ... 10 ° C, the compressor shuts off, the shut-off valve opens and the forced circulation of the refrigerant is replaced by natural, the refrigerant boiling in the evaporator is transferred to the air-cooled condenser. The liquid cooled under the force of gravity. if it is not possible to place the condenser on the evaporator to the evaporator, a freon pump can be used.
In the event of a natural cold, the best efficiency of using refrigerants is achieved when the temperature difference between the refrigerant and the coolant is minimal. So something called to increase the cooling capacity of the installation. regenerative cycle, in which the liquid refrigerant is additionally cooled after leaving the condenser; lowering the temperature of the refrigerator by 1 ° C can increase the efficiency of the equipment by 1%. Of course, cooling the refrigerator increases the cycle time, so its capacity is limited. Restrictions can be leveled when using an external source of heat removal up to the thermostatic cover; for this purpose, special units with the function of collecting cold are used. An industrial cold accumulator is a container-shaped cooling device filled with substances with high heat capacity. There are two types of such units:
1) an artificial cold accumulator that uses the cold released during the operation of the cooling device during periods of low heat loads;
2) a natural cold accumulator that collects environmental cold in winter.
Thus, the energy efficiency of cold-storage battery coolers stems from the
ability to reduce the cooling capacity of the device due to the accumulation of ice water and ice reserves, as well as operating at the highest loads with a constant temperature of ice water.
Air conditioning systems in the accumulation of natural cold is an actively developing innovative segment of engineering systems of buildings, structures and autonomous structures. The size of the climate equipment market, according to the Association of Climate Industry Enterprises, is growing more than 10 times a year, 12-15% and can reach 30% under the optimistic scenario [1]. There are a number of reasons for this rapid growth. First of all, it is the growth of demands on quality of life. A healthy lifestyle is not only a personal choice, but in many cases becomes part of the employer's "corporate culture". The second is the deterioration of environmental quality due to urbanization, motorization and global climate change. Natural cold The formation of favorable environmental parameters in the home environment is the main task of life support systems. Creating a comfortable environment implies the ability to maintain individual microclimate parameters (temperature, humidity, mobility, gas composition of the air, its aerosol pollution, acoustic pressure, insulation and room lighting) in strict
compliance with sanitary and hygienic standards and requirements. Thus, in the most general case, the air conditioning system can be considered as a single set of engineering subsystems (ventilation, heating, cooling, etc.), which ensures the maintenance of the necessary parameters of the internal environment (rooms, groups of rooms). buildings), regardless of the external climatic conditions, taking into account the architectural and construction and thermal-physical properties of the surrounding structures.
Obviously, for convenience and technical conditions, depending on the specific requirements, some subsystems may or may not exist at all, or may have limited performance and range regulation zone. A special type of climate systems are technological air conditioning systems. For many modern industries, the technological environment with the available parameters of air is the sional nature and quality and price determination products. In the future we will only talk about systems since the object of convenient air conditioning you technological air conditioner, as a rule, is a single or small batch and can manage them due to the improvement of technological processes and methods of successful development on a large scale. Regardless of the type of system, the quality of the project is determined by the range supported by the solution air conditioning control zone and the amount of capital and operating costs. Because more than 40% of all final energy is produced by mining in our country, which is consumed by life support systems, and the cost of energy sources is constantly rising, then the reduction of operating costs is a priority for air conditioning system developers. is gaining the attention of experts at the moment. To natural refrigerants such as hydrocarbons, carbon dioxide, water, air. This can be predicted. The main trend of the XXI century will be the transition from synonymy to aesthetics to natural refrigerators.
In addition to work on improving thermodynamics in the accumulation of natural cold, in the development of new equipment, great attention is paid to the reduction of unnecessary technical processes, friction and losses due to increased resource operation of mechanical units. A characteristic feature of air conditioning systems is a wide annual, and the manufacturer's daily regulatory scope is the parameters of compressors and ventilation equipment to cover changes in external climatic conditions. Capacity management can be done using a reshort belt operating mode or with the use of a variable frequency drive. It is known that the suspension in the base friction units occurs and stops in start-up modes, in the same modes the minimum temperature deformations in the maximum joints, so the transition to frequency regulation is reasonable and promising. Consider that in these climate equipment the speed drive can be reduced to a few hertz.
In order to compensate for the suspension during continuous operation, the designs in these modes developed a metal selective transmission effect. VOC additives from a mixture of lubricating oils and freon on the friction bearing surface [6]. Others use friction as a means of reducing wear and heat generation in the region - this is the use of new composite materials, for example, graphite-reinforced fluoroplastics roofing or bronze. The above growth trends (efficiency
(energy) price, price, weight and dimensions) of life support systems are largely traditional. Such an evolution increases the efficiency of this way on stocks, rarely by a few percent. However, what is needed is high air conditioning systems due to lack of energy sources, which forces us to look for new ways to solve this problem. In fact, Air Conditioning in the field of creation and modernization of air conditioning systems in search of new directions to solve such design problems. The development approach clearly differs from the solutions that are effective in modernizing life support systems in new buildings, which can mean the nationalization of existing housing and office supplies.
Cooling scheme using refrigerators and fan belts is often used in the design of air conditioning systems for public buildings in the accumulation of natural cold. Refrigerators are designed to cover the maximum heat generated in the building. However, the maximum load is often short-lived and often the refrigerators operate at 40-60 percent of their maximum capacity.
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