Investigation of Transient Process of Heat Carrier Temperature of Water to Air Heat Exchanger

In this numerical study, 4 types of hybrid nanofluid, including Ag-MgO/water, TiO2-Cu/water, Al2O3-CuO/water, and Fe3O4-multi-wall carbon nanotube/water, have been considered potential working fluid in a single U-tube borehole heat exchanger. The selected hybrid nanofluid is then analyzed by changing the volume fraction and the Reynolds number. Based on the numerical results, Ag-MgO/water hybrid nanofluid is chosen as the most favorable heat carrier fluid, among others, considering its superior effectiveness, minor pressure drop, and appropriate thermal resistance compared to the pure water. Moreover, it was indicated that all cases of Ag-MgO/water hybrid nanofluid at various volume fractions (from 0.05 to 0.20) and Reynolds numbers (from 3200 to 6200) could achieve better effectiveness and lower thermal resistances, but higher pressure drops compared to the corresponding cases of pure water. Nevertheless, all the evaluated hybrid nanofluids present lower coefficient of performance (COP)-improvement than unity which means that applying them as working fluid is not economically viable because of having higher pressure drop than the heat transfer enhancement.

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Development of a heat exchanger device- regenerator for high-temperature gas heating

Proceedings of the higher educational institutions ENERGY SECTOR PROBLEMS ◽

10.30724/1998-9903-2019-21-5-38-49 ◽

2019 ◽

Vol 21 (5) ◽

pp. 38-49

Author(s):

D. A. Bazykin ◽

A. I. Sukhov ◽

A. V. Barakov

Keyword(s):

High Temperature ◽

Heat Exchanger ◽

Heat Carrier ◽

High Performance ◽

Combustion Products ◽

Low Grade ◽

Technical Literature ◽

Gas Processing ◽

Gas Heating ◽

Gaseous Media

The urgency of the task is to develop a heat exchanger-regenerator designed for high- temperature heating of gaseous media, which are used in various technological schemes of the petrochemical, gas processing, energy and other industries. The developed heat exchanger has high performance due to the developed heat exchange surface, reliability due to the fact that the inner and outer pipes are movable relative to each other with linear dimensions compensation, it is simple to manufacture, does not require the use of an intermediate heat carrier, can be used as a heating coolant combustion products of untreated, low-grade gaseous fuel. At the same time, it is possible to equip the developed apparatus with a convection heat exchanger for more efficient use of the heat of the fuel combustion products. The article describes the proposed design, the principle of operation of this heat exchanger-regenerator. A review of the technical literature has been carried out, the main advantages of the device are shown in comparison with the currently known domestic and foreign counterparts. The paper presents the main calculated dependencies used in the design, as well as the results of the calculations. The possibility of using the proposed heat exchanger as part of a gas turbine unit used as an autonomous power source is considered, as well as information about technological processes in which it can be used. In conclusion, we can say that the developed heat exchanger has high performance, differs in the ability to work at high temperatures without violating the integrity of the structure, does not require the use of an intermediate heat carrier, and is to be used in many industries.

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Energy performance and cost analysis of some borehole heat exchanger configurations with different heat-carrier fluids in mild climates

Geothermics ◽

10.1016/j.geothermics.2016.09.006 ◽

2017 ◽

Vol 65 ◽

pp. 158-169 ◽

Cited By ~ 12

Author(s):

Giuseppe Emmi ◽

Angelo Zarrella ◽

Michele De Carli ◽

Mirco Donà ◽

Antonio Galgaro

Keyword(s):

Heat Exchanger ◽

Cost Analysis ◽

Heat Carrier ◽

Energy Performance ◽

Borehole Heat Exchanger

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Performance analysis of coaxial heat exchanger and heat-carrier fluid in medium-deep geothermal energy development

Renewable Energy ◽

10.1016/j.renene.2020.12.109 ◽

2021 ◽

Vol 168 ◽

pp. 938-959

Author(s):

Yuting He ◽

Min Jia ◽

Xiaogang Li ◽

Zhaozhong Yang ◽

Rui Song

Keyword(s):

Heat Exchanger ◽

Performance Analysis ◽

Heat Carrier ◽

Geothermal Energy ◽

Energy Development ◽

Carrier Fluid ◽

Deep Geothermal Energy

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Determining the kinetic and energy parameters for a combined technique of drying apple raw materials using direct electric heating

Eastern-European Journal of Enterprise Technologies ◽

10.15587/1729-4061.2021.224993 ◽

2021 ◽

Vol 1 (11 (109)) ◽

pp. 33-41

Author(s):

Oleksandr Savoiskyi ◽

Valerii Yakovliev ◽

Viktor Sirenko

Keyword(s):

Electric Field ◽

Heat Carrier ◽

Field Intensity ◽

Raw Materials ◽

Electric Heating ◽

Convective Drying ◽

Technological Parameters ◽

Energy Parameters ◽

Carrier Temperature ◽

Combined Technique

The development of technology and drying equipment tackles a triune task: to intensify drying processes, to save energy, to ensure that proper product quality is achieved. This issue is resolved by modern advancements by supplying thermal energy throughout the entire sample volume. The simplest option among the known techniques is to heat wet raw materials by passing an electric current directly, with an external blowing by a hot heat carrier. This paper reports an experimental study of the combined process of drying apple raw materials using direct electric heating. The influence of control factors such as the field intensity and a heat carrier temperature on the kinetic parameters of the process has been determined, namely: the duration of the combined drying of apples, the rate of moisture removal, and a change in the temperature of the sample. It was established that the application of additional electric heating with an electric field intensity of 20–40 V/cm during convective drying with a heat carrier temperature of 25–55 °C reduces the duration of apple dehydration by 3‒5 times. Permissible limits for changing the combinations of basic technological parameters have been determined, as well as the rational modes for treating raw materials in order to ensure the predefined quality of finished products. Such combinations of technological parameters of heating, in particular the intensity of the electric field and air in the dryer, are 30 V/cm+40 °C, and 25 V/cm+55 °C. The energy parameters of the proposed combined technique of drying apple raw materials have been determined. It was established that the specific energy consumption for the removal of 1 kg of moisture at direct electric heating is 2,350–2,400 kJ/kg (0.66 kWh/kg). The study performed could provide a prerequisite for devising an energy-efficient technique for the combined drying of fruit and vegetable raw materials using direct electric heating

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Justification of the Flow Characteristics of the Recuperator for the Thermal Preparation of Machinery and Equipment Units

Metal Working and Material Science ◽

10.17212/1994-6309-2020-22.4-82-93 ◽

2020 ◽

Vol 22 (4) ◽

pp. 82-93

Author(s):

Roman Chernukhin ◽

◽

Aleksey Dolgushin ◽

Nikolai Kasimov ◽

Vladimir Ivancivsky ◽

...

Keyword(s):

Computer Simulation ◽

Heat Exchanger ◽

Heat Exchange ◽

Heat Carrier ◽

Thermal Regime ◽

Flow Characteristics ◽

Analytical Determination ◽

Thermal Processes ◽

Hydraulic Systems ◽

Technological Processes

Introduction. Machines and equipment in its composition may contain hydraulic systems to ensure the functioning of the main and auxiliary systems. It is known that a common disadvantage of hydraulic systems and drives is the dependence of the viscosity of the applied fluids on temperature. A noticeable part of technological machines and equipment is located in unheated or poorly heated industrial premises and a change in the viscosity of working fluids with a decrease in the ambient temperature can significantly affect the parameters of technological processes. An important factor in ensuring the stability of the technological processes parameters is the degree of preparation of machines and equipment for operation at low temperatures or in conditions of fluctuating temperature conditions. In this regard, the question arises of ensuring the required temperature of technical fluids before turning on machines and equipment, and maintaining the required thermal regime during the operation of its units and assemblies. One way to solve this problem is to use external heat sources. Various heat exchange devices can serve as such sources. In the heat exchange device, the heat carrier is heated, which is then fed into the heat exchange jacket of the machinery and equipment units. Both liquid and gaseous media are used to heat the coolant in the heat exchanger. In the latter case, the heat exchanger is called a recuperator. The efficiency of the recuperator is determined by its design and flow characteristics. There are methods for the analytical determination of both the design and flow characteristics of the recuperator, but these methods are quite laborious. The use of computer simulation of thermal processes makes it possible to successfully solve the calculation problem, and also significantly reduces the design time of heat exchangers. The aim of the work is to substantiate the flow characteristics of the recuperator for maintaining the thermal regime through computer simulation. The research method is computer simulation of thermal processes, which is implemented using the SolidWorks software package from Dassault Systems and its Flow Simulation application for simulating thermal processes in scientific research and engineering. Results and discussion. Simulation carried out in stationary and non-stationary modes made it possible to determine the effect of pump performance on the temperature of the coolant at the outlet of the recuperator. It is found that when the heat carrier flow rate is more than 20 l/h, its temperature does not reach the required values, despite the fact that the gases leaving the recuperator have a significant residual temperature. The efficiency of the recuperator is assessed by determining the exergy efficiency. Based on the data obtained, the most preferable are the pump productivity values lying in the range from 4 to 20 l/h.

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Calculation of the Efficiency of Regenerative Air Heat Exchanger with Intermediate Heat Carrier

Journal of Construction Research ◽

10.30564/jcr.v3i1.3235 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Mikhail Ivanovich Nizovtsev ◽

V. Yu. Borodulin

Keyword(s):

Heat Transfer ◽

Mathematical Model ◽

Heat Exchanger ◽

Heat Carrier ◽

Heat Transfer Process ◽

Maximum Temperature ◽

Operating Parameters ◽

Air Flow Rate ◽

Filling Height ◽

Temperature Efficiency

The study deals with a new regenerative air heat exchanger with an intermediate heat carrier used in the systems of room ventilation. A physical and mathematical model of the heat transfer process is proposed. The influence of design and operating parameters on the temperature efficiency of the heat exchanger is analyzed. The possibility of a significant increase in its efficiency with a decrease in the packing diameter is shown. As a result of calculations, it was found that with a decrease in the filling height, the maximum temperature efficiency shifted towards a decrease in the air flow rate from its value determined from the equality of water equivalents of liquid and air.

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INCREASING THE EFFICIENCY OF HEAT LOAD CONTROL IN CENTALIZED HEATING NETWORKS

Architecture and Engineering ◽

10.23968/2500-0055-2021-6-3-29-41 ◽

2021 ◽

Vol 6 (3) ◽

pp. 29-41

Author(s):

Alexander Shkarovskiy ◽

◽

Anatolii Kolienko ◽

Vitalii Turchenko ◽

◽

...

Keyword(s):

Energy Consumption ◽

Heat Carrier ◽

Heat Load ◽

Heat Supply ◽

Optimal Operation ◽

Heat Losses ◽

Load Control ◽

Heating Systems ◽

Carrier Temperature ◽

Heating Networks

The paper presents the results of studies aimed to increase the efficiency of centralized heating networks by improving heat supply control at the plant and at the local level. With this in view, we considered issues of choosing the optimal heat supply schedule and its influence on the efficiency of heat generation, transportation and use, as well as the influence of the heat carrier temperature on heat losses at the corner of the temperature curve. We also studied the influence of the heat carrier temperature in the return pipe of heating networks on the operation of heat generators by using various control methods. Another issue considered in the course of the study was the issue of ensuring the hydraulic and thermal stability of heating networks and heating systems connected to them by using the combined control method. The methodology of the study was based on the analysis of heat balance equations for the steady-state operation of a complex including a heating network and a building’s heating system. As a result, we obtained relationships that make it possible to determine the variation in the heat carrier flow rate and temperature depending on the heat load, as well as the reduction in energy consumption for heat carrier transportation. Recommendations were developed for the introduction of combined heat load control. A scheme for the reconstruction of central heat stations is proposed. The scientific and practical results of the study can be used to prevent significant heat losses, ensure optimal operation of heating networks, heat generators, and heating systems, reduce energy consumption, and increase the overall efficiency of centralized heating networks.

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