In the article, a heating scheme of a hybrid heat and hot water supply system based on vacuum solar collectors and heat pump devices for country houses and model houses is proposed. The operating procedure of the hybrid heat and hot water supply system is presented. The hybrid heat and hot water supply system is connected to a vacuum solar collector and a heat pump device connected to an underground heat source (sewage well) through a tank accumulator. Heat-technical calculation of tank-accumulator and heat pump device is given. The energy consumption of the heat pump device used in the hybrid heat supply system is 2.5 kW, and the heat and hot water supply system produces 22, 65 kW of heat energy for the tank accumulator, which is 20÷25 more than boiler devices and electric heating devices in traditional heat and hot water supply systems. It is based on the fact that it has up to 25 times energy efficiency.
Taking into account the meteorological climate parameters of the Kashkadarya region, the heating season is 135 days, in the hybrid autonomous heat supply system of the proposed rural houses and model houses, it is possible to save 73,386 kW of electricity or use 30÷40 tons of conventional fuel due to the use of only a 2.5 kW heat pump device. It is scientifically proven that savings can be made.
This study aimed to assess the heat tolerance of crossbred female calves using three different indicators: Iberia Heat Tolerance Coefficient, Benezara Coefficient of Adaptability, and Dairy Search Index. Heat stress is a major concern in livestock production, particularly in regions with high temperatures. Understanding the heat tolerance of animals is crucial for their well-being and productivity. In this study, a total of X crossbred female calves were evaluated for their heat tolerance using the aforementioned indicators. The results indicated a significant variation in heat tolerance among the crossbred calves, as reflected by the different coefficients and indices. These findings provide valuable insights into the selection and management of crossbred female calves for improved heat tolerance, leading to enhanced productivity and animal welfare in heat-stressed environments.
Shell and tube heat exchangers are fundamental components in the chemical industry, responsible for efficient heat transfer processes critical for various manufacturing operations. As the chemical industry continues to evolve and strive for increased efficiency and sustainability, the integration of artificial intelligence (AI) technologies has emerged as a promising avenue to optimize the operation and performance of these heat exchangers. This paper explores the current state of shell and tube heat exchangers in the chemical industry and investigates the pivotal role that AI plays in improving their efficiency, reliability, and overall effectiveness. We delve into the applications of AI in the design, monitoring, and control of heat exchangers, highlighting key benefits and challenges associated with its implementation.
The article presents the world forecast for the development of the heat and power industry for the production of heat and electricity. It is noted that the increase in the production of types of energy is associated not only with an increase in the consumption of fossil fuels, but also with the deterioration of the environmental situation. Taking into account the foreign experience of using solar installations producing thermal energy and favorable climatic conditions of the Republic of Uzbekistan, the prospects of using solar air heaters for heating existing residential buildings were discussed. providing residential buildings and drying plants with heat energy without expensive constructive and technological solutions, as well as carrying out rapid heating of premises. Such a collector, despite the fact that the air has a lower heat capacity, can provide an even distribution of heat, it is well regulated both in temperature and in the amount of air supplied. In addition, collectors operating under natural convection conditions can be successfully combined with a traditional heating system.
At the same time, the article also shows a positive experience of using air heaters in drying technology. In particular, an industrial prototype of a solar air heater was used to dry the windings of transformers used in pumping stations of irrigation systems for the water sector of the Republic. It is shown that the use of air heaters allows saving not only significant fuel, energy and monetary resources, but also strengthening the energy security of the Republic of Uzbekistan.
SUMMARY
On the article "The role of solar heaters in the thermal energy industry and the prospects for their development in the Republic of Uzbekistan"
The article discusses the use of solar heaters in the conditions of the Republic of Uzbekistan during the heating season to support traditional heating systems.
As is well known, solar energy is the most prepared form of all existing alternative energy sources, which can be used, partial and in some cases completely, as a replacement to the heating system in the residential or public buildings. More acceptable devices that provide this heating can be considered solar air heaters.
Such a collector, despite air’s low heat capacity, can provide an even distribution of heat, well-regulated both by temperature and by the amount of air supplied. The Republic of Uzbekistan is in a favorable geographical area for such collector because solar energy in the country can be practically used for 10 months of the year, of course, considering the variable nature of solar insolation.
The author of the article shows that with the volume of housing stock of Uzbekistan at 507,5 million m2 (private housing fund is 504,1 million m2 as of January 1, 2018), 4 months’ heating cost during the heating season can make up 4,6 trillion soums.
Preliminary calculations show that the use of solar air heaters in buildings heating systems, at least as an auxiliary source of thermal energy, provides significant savings in natural gas.
For example, during the coldest months in the country – December and January- the savings can comprise 0,26 to 0,23 trillion soums. The article presents an experimental sample of the solar air heater, as well as describes the positive results of using solar air heaters for drying transformer windings.
The aim of the study is to develop a new design of a self-regulating water heat accumulator with temperature stratification of water, which excludes mixing of heating and heated coolants entering the accumulator from the charging and discharging circuits based on the natural stratification of water in the tank under the influence of volumetric (Archimedean) forces under conditions of forced circulation of the coolant.
Based on the analysis of the world experience in the development of designs of water heat accumulators with temperature stratification of water and the stability of the stratified (stratified) flow of the coolant in the volume of the accumulator, a new design of a self-regulating water accumulator is proposed.
The advantages of using self-regulating stratification water heat accumulators in solar heat supply systems are considered. It is shown that the use of stratification for short-term and long-term thermal accumulation leads to an increase in the use of solar heat by 15-20% compared to batteries with completely mixing water. In hot water systems, these batteries can provide earlier preparation of hot water with the required temperature for consumers.
Clothing insulation is one of the important factors of human thermal comfort assessment. Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radioactive influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials. Heat flow is an inevitable consequence of contact between objects of different temperature. Thermal insulation provides a region of insulation in which thermal conduction is reduced or thermal radiation is reflected rather than absorbed by the lower-temperature body. The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. Heat energy can be transferred by conduction, convection, radiation or when undergoing a phase change. For the purposes of this discussion only the first three mechanisms need to be considered. The flow of heat can be delayed by addressing one or more of these mechanisms and is dependent on the physical properties of the material employed to do this. Predicting the pattern of clothing adjustment to climate change can provide important basis for thermal comfort and energy consumption analysis. To achieve reliable results, it is necessary to provide precise inputs, such as clothing thermal parameters. These values are usually presented in a standing body position and scarcely reported locally for individual body parts. Moreover, as an air gap distribution is both highly affected by a given body position and critical for clothing insulation, this needs to be taken into account.
This study investigates the heat transfer efficiency of spiral pipe and round pipe configurations within boiler gas turbine systems. Heat transfer efficiency is a critical factor in the performance and energy efficiency of industrial systems, particularly in power generation applications. Using computational modeling and simulation techniques, we assess the thermal performance of spiral pipe and round pipe designs under various operating conditions typical of boiler gas turbine systems. Our analysis focuses on heat transfer rates, pressure drops, and overall system efficiency. The findings provide insights into the comparative advantages and limitations of spiral pipe and round pipe configurations in enhancing heat transfer efficiency within boiler gas turbine systems.
In the article, in calculating the volumetric heat distribution in a water tank heat
accumulator, the location of water tanks along a flat wall and the degree of efficiency of hot
air flow heat accumulation along their gaps were determined.
The article considers the graphical method of solving the modular equation depending on three parameters. Two functions are defined by the right and left sides of the equation. Using bounded and unbounded properties of defined functions, the existence conditions and the number of solutions of modular equation solutions depending on the parameters are shown. In addition, the questions about which values of the parameters of the considered modular equation has solution, and in which quadrants the graphs of the defined functions are located, have been fully answered.
The article discusses the prospects for the development of the heat and power industry in the Republic of Uzbekistan. It was noted that according to the development concept of the Republic of Uzbekistan until 2035, the expected growth in electricity consumption in the Republic will be approximately from 2000 to 3156 kWh/person. This growth in electricity production is planned to be achieved by increasing the production of renewable energy sources (RES) in the structure of generating capacities from 12.7% to 19.7% by 2025, upgrading existing plants, building new combined-cycle gas plants (CCGPs) and further construction of a nuclear power plant (NPP).
Given that in the coming years to 85% of the thermal and electric energy in the Republic is generated in thermal power stations that use natural energy resources such natural gas, coal and fuel oil, and also given the greater depreciation of equipment stations and as a consequence their low efficiency, the authors emphasize the importance of using to generate these types of energy modern combined cycle technology.
It is indicated that currently there is a wide technical and industrial cooperation of the main foreign gas turbine manufacturers in the world. In the world, the main manufacturers of such equipment are three companies - General Electric (USA), Siemens - Westinghouse (Germany - USA) and Alstom (France, Switzerland, Sweden).
Variants of combined steam and gas turbine units (GTU) have been developed. As a result of the GTU operation, the gases used in the installation were proposed to be used in the steam power cycle.
Advantages of CCGP: combined-cycle plants can achieve an electric efficiency of more than 60 %. For comparison, the efficiency of steam power plants operating separately is usually in the range of 33-4 %, for gas turbine plants - in the range of 28-42 %; low cost per unit of installed capacity; combined-cycle plants consume significantly less water per unit of electricity generated compared to steam power plants; short construction time (9-12 months); there is no need for constant fuel supply by railway or sea transport; compact dimensions allow you to build directly at the consumer (factory or inside the city), which reduces the cost of power lines and transportation of electric energy; more environmentally friendly compared to steam power plants.
The disadvantages of CCGP include: the need to filter the air used for fuel combustion; restrictions on the types of fuel used. As a rule, natural gas is used as the main fuel, and diesel fuel is used as a backup fuel. The use of coal as fuel is only possible in installations with in-cycle coal gasification, which greatly increases the cost of building such power plants. This implies the need to build expensive fuel transportation communications - pipelines; seasonal capacity restrictions. maximum performance in winter.
However, despite the listed disadvantages of CCGP, at this stage of development of the Republic, combined-cycle plants can produce electricity with a high efficiency, thereby significantly saving natural gas. Approximate calculations show that the technical re-equipment of the domestic heat power industry using gas-turbine and combined-cycle technologies and environmental protection equipment developed in the world will allow saving natural gas annually in the amount of approximately 1010 m3, which in monetary terms will amount to 3 trillion soums. In General, it is concluded that
1.to solve the country's energy problems, it is necessary to accelerate the introduction of REI, technically re-equip the domestic heat and power industry using gas turbine and combined-cycle technologies developed in the world.
2.in power plants where the fuel balance contains a large proportion of fuel oil or coal, but there is also natural gas, in an amount sufficient to power the gas turbine, it may be advisable to thermodynamically more efficient gas turbine superstructures.
3.to implement the tasks of modernization and reconstruction, involve the private sector in the energy sector on the basis of public-private partnership. Create the necessary regulatory framework and technical infrastructure.
The results of research on the calculation of the temperature field and heat fluxes through
the translucent coatings of flat solar installations and the proposal of appropriate
expressions for determining their values are presented
In this paper, we proved the unique solvability of the local boundary value problem with the Frankl condition for a degenerating of mixed type equation with a fractional derivative
In this work an existence and uniqueness of solution of non-local boundary value problem with discontinuous matching condition for the loaded parabolic-hyperbolic equation involving the Riemann-Liouville fractional derivative have been investigated. The uniqueness of solution is proved by the method of integral energy and the existence is proved by the method of integral equations.