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32ENERGY SAVING IN INDUSTRIAL VENTILATION SYSTEMS Bolat E.A.1, Sharipov R.Zh.2
1Bolat ErasylAsanuly - Undergraduate, DEPARTMENT OF ENGINEERING SYSTEMS AND NETWORKS, INSTITUTE OF ARCHITECTURE AND CONSTRUCTION; 2Sharipov Rashid Zhapparovich - Candidate of Technical Sciences, Professor, DEPARTMENT OF ENGINEERING AND INFORMATION TECHNOLOGIES, KAZAKH GERMAN UNIVERSITY, ALMATY, REPUBLIC OF KAZAKHSTAN
Abstract: in the article, one of the global trends in the economy today is the use of energy-saving technologies. Reducing the energy consumption of heating, ventilation and air conditioning systems is becoming increasingly important due to rising fossil fuel prices and environmental problems. Therefore, finding new ways to reduce energy consumption without compromising the comfort and quality of air in buildings is a constant research task. Keywords: industrial ventilation, energy saving, technology, evaporative, underground heat preservation,recuperator, cold ceiling, ejector.
The object of research is industrial enterprises that have the potential to increase energy efficiency.
Relevance of the work. Ventilation and heating systems consume from 10% (chemical) to 70% of all heat and energy resources consumed by the enterprise, depending on the industry. Solving the problem of energy saving in these systems has a significant impact on the cost of production.
In this regard, the development of new solutions aimed at saving heat and electricity in ventilation and heating systems of various industries, as well as improving their sanitary and hygienic efficiency, is an urgent issue of national economic importance.
The purpose of the work is to identify and study the parameters that affect the consumption of heat and electricity by ventilation and air heating systems in the industry, and to develop technical solutions that allow these systems to achieve a reduction in heat energy costs by controlling the specified parameters.
The share of industry in Kazakhstan'S GDP is 34.1%. Currently, in the structure of the economy of Kazakhstan, industry occupies a third. In the process of industrialization, the emphasis in industry is gradually moving towards the manufacturing industry, although the level of its development remains relatively low. Along with the radical modernization of technological processes and equipment, the modernization of domestic industry is impossible without a significant reduction in heat energy consumption, ensuring satisfactory working conditions. Unfortunately, our country is far behind the leading industrial countries in terms of such an important indicator as the amount of energy, the unit of output. Energy saving is an integral part of industrial facilities. Ventilation and heating systems of industrial enterprises are the most important and sometimes the main consumer of heat and electricity. Therefore, reducing the energy consumption of heating and ventilation systems will reduce the cost of production and, accordingly, increase its competitiveness.
Energy-efficient LPG systems can be created by reconstructing traditional systems for strategic use of existing parts of the system. Recent studies have shown that the combination of existing air conditioning technologies can provide effective solutions for energy saving and thermal comfort. In this article, various technologies and approaches are studied and discussed, as well as opportunities to increase the productivity of LH systems in order to reduce energy consumption are shown. For each strategy, a brief description is given first, and then, by analyzing previous studies, the effect of this method on energy saving of LH is studied. Finally, a comparative study is conducted between these approaches.
Fig. 1. Energy-saving heating and ventilation systems
1. Evaporative cooling systems
Cooling during evaporation is a physical phenomenon in which the evaporation of a liquid into the surrounding air cools an object or liquid in contact with it. The amount of heat needed to evaporate the liquid is taken from the environment. The greater the difference between the two temperatures, the greater the cooling effect. Evaporative cooling is particularly well suited for climate zones with high air temperature and low humidity, such as Kazakhstan. Evaporative coolers are compact, noiseless, do not consume much energy, and can save up to 95% of circulating water, as well as eliminate CO2 and other emissions. They are easy to use and maintain, efficient and safe. There are several types of evaporative cooling systems.
Indirect evaporative cooling in this approach, outdoor air is used to cool the room without mixing indoor and outdoor air flows. The outside air passes through the thermal coolant of the ventilation unit and is discharged back, and the recirculating air in the room passes through the thermal coolant and returns to the room. When the outdoor temperature is lower than the indoor air temperature, it can be used to cool the room [2].
Fig. 2. Indirect evaporative cooling system
Since the moistened air does not mix with the incoming fresh air, the air humidity does not increase, and cooling does not depend on the level of humidity of the incoming air. When supplying 1 kg of moisture to the air with an adiabatic humidifier, a coolness of 680 W is formed. Since a single adiabatic humidifier can produce up to 1000 kg of
moisture per hour, consuming only 300 watts of electricity, such installations have a high potential for low-cost cooling in ventilation systems with exhaust air. With the help of adiabatic cooling nozzles, the output power increase can be 20%, and in very hot or dry climates — up to 60% [1].
2. Underground HV systems
At depth, the Earth has a relatively constant temperature, which is colder than the air temperature in summer and warmer than the air temperature in winter. In the cooling mode in this system, the operating heat is transferred from the ground circuit, which provides a lower temperature than the external ambient temperature. During winter heating works, the opposite is obtained from the warm circuit. It was widely used in Europe and the United States from 2004 to 2007, as well as about 60% of all social LSD installations in Korea in recent decades . In China, the use of this system is growing rapidly ; From 1985 to 2007, the number of patent applications for this system increased: 278 patents were issued and 157 patents are being considered . In addition, about 1.1 million underground heat pumps are installed worldwide. Compared to standard technologies such as steam compression systems, ground-based heat pumps produce less noise, provide environmental safety, and can reduce greenhouse gas emissions by 66% or more compared to conventional LNG systems.
3. Heat preservation
Heat energy storage is achieved through various technologies. Depending on the specific type of technology, it allows you to store excess heat energy for several hours, days, months and use it. Examples of use: balancing energy needs between day and night, maintaining summer heat for heating in winter, or winter cold for cooling summer air ( seasonal accumulation of thermal energy). Storage environments include water or ice reservoirs, natural earth or Indigenous rocks accessed through wells with the help of heat exchangers, deep aquifers between impermeable layers; shallow pits filled with gravel and water and insulated from above, as well as eutectic solutions and phase transition materials . Both seasonal and short-term heat conservation is considered an important tool for cheap balancing of the high share of variable electricity generation from renewable energy sources and for integrating the electric and thermal sectors, which are almost or completely powered by renewable energy sources, into energy systems. Cooling water storage tanks are usually charged with water at a temperature of 4-6 ° C. A complete cooling water storage system can reduce the maximum cooling needs of electricity by 80-90% compared to conventional cooling systems, and a complete glacial heat storage can reduce the power consumption of the system by 5%, and save 55% of the electricity required for cooling per month.[3]
UTES (underground storage of thermal energy), which can contain geological layers ranging from Earth or sand to solid rocks or aquifers. UTES technologies:
Ates (reservoir of heat energy of the aquifer). The ATES reservoir consists of a doublet consisting of two or more wells in a deep aquifer located between impenetrable geological layers above and below. Half of the doublet is intended for receiving water, and the other half is intended for pumping, so the aquifer is stored in the hydrological balance without clean prey. A heat sink (or cold) is water and the substrate it receives. The Reichstag building in Germany has been heated and cooled by ATES stores in two aquifers of different depths since 1999.
BTPP (borehole accumulator of thermal energy). Btes stores can be manufactured in which holes can be drilled , and consist of hundreds of vertical wells with a diameter of usually 155 mm (6.102 inches). Systems of all sizes have been built, including many large ones.
5. Heat recovery (recovery)
Industrial suction and exhaust units with a recuperator are devices designed to supply and receive air from large rooms, and sometimes from entire buildings. The capacity of such recuperators ranges from 5,000 to 200,000 cubic meters per hour. Most often, industrial suction and exhaust units with air recovery are used in large offices, cottages, industrial premises and in places where large air consumption is required. In addition, the greater the volume of air supplied and removed from the room, the more it will be necessary to have an air recuperator in the air treatment device, because. savings from it come not in thousands, but in tens and hundreds of thousands of tenge.
As a result, at the stage of purchasing a recuperator, you will receive a payment of 1.25-2 times more than when using classic ventilation systems, and the breakdown period of these investments is a maximum of 5 years, and the service life of these devices is 15 years.
6. Other strategies
Numerous studies on energy conservation have been conducted for HV systems, which are the result of the use of materials that have an increased ability to absorb, store, and emit mass or heat. Sometimes changing the design criteria allows air conditioning systems to work efficiently without requiring additional costs. The solution here is to use other methods to solve the problem, although this can increase the initial cost of the system. In such cases, an economic comparison is necessary to determine whether the new system will provide reimbursement of additional costs within a reasonable period of time.
One of the solutions is cold ceilings.The principle of operation of the cold ceiling system differs from other methods of cooling using a coolant. Capillary linings are installed on the ceiling of the room, forming a single hydraulic contour of a special structure. Distilled water circulates through the main pipes, which cools the surface and objects in the room. 80% cooling occurs by absorbing radiation and only 20% by convection. This method of cooling has a number of advantages: saving electricity (up to 30%); silent operation; compactness of the unit(h 10 cm); no drafts and humidity; the ability to install any shape on the ceiling surface; completely hidden installation of all elements; minimal maintenance costs.
Fig. 3. Cold ceilings
Ejector cooling technology is another energy-efficient strategy that is characterized by Ease of installation, maintenance and design compared to conventional steam compression refrigeration systems. Air cooling is carried out by spraying small drops of water into the air stream in the heat exchanger-ejector. With this type of cooling, it is possible to increase the total flow pressure in the region of subsonic velocities (the so-called thermogasodynamic effect). This process can be carried out in a specially designed device - a heat exchanger. Air conditioning systems with ejector heat exchangers allow, in addition to air conditioners, to maintain the set air parameters in individual rooms due to heat treatment, as well as in amplifiers. These systems have their own cost and individual advantages, for example, an increase in the efficiency of air treatment in an air conditioner by 30%, electricity consumption up to -20%, and a minimum number of ventilation pipes.[3] Conclusion
In recent years, the impact of various strategies of LH systems on energy saving in a commercial building in Dahran, Saudi Arabia, has been studied. Their results showed that using variable air volumes instead of a unitary system can save about 22% of energy. They also found that an increase in room temperature by 3 ° C leads to savings of 17%. It was found that changing the operating schedule of the fan allows you to save about 21.4%. The use of a set temperature of 28 ° C in busy periods led to an savings of 18%. However, they came to the conclusion that about 25% of energy savings can be achieved in a combination of different strategies for the operation of LH, that is, a hybrid of the two systems. The results of the simulation showed through studies that the first studied system is energy efficient and has little impact on the environment. However, they noted that for a complete analysis, it is necessary to take into account investment costs, maintenance costs and other factors. By repeating this experience at any production site in Kazakhstan, we can determine that the energy saving stategia of the first system is the most effective for our climate. But depending on the type of production, local weather conditions, it is necessary to create a hybrid of the first system.
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