scholarly journals MODELING OF A DOUBLE CIRCULATION RECUPERATOR’S HEAT WORK

2021 ◽  
Vol 1 (38) ◽  
pp. 106-115
Author(s):  
N. Volianska
Keyword(s):  
Mathematical Model ◽  
Energy Efficiency ◽  
Thermal Performance ◽  
Environmental Performance ◽  
Heat Exchangers ◽  
Energy Resources ◽  
Waste Products ◽  
Thermal Operation ◽  
Heat Units ◽  
Important Means

Utilization of heat from waste products of heat units’ combustion is one of the most important means of saving fuel and energy resources and improving the environmental performance of the enterprise. Improving the design of heat recuperators and increasing their energy efficiency by improving thermal performance is based primarily on the development of new and improvement of existing methods for calculating heat exchangers. In this paper, based on the method of elementary heat balances, a mathematical model of the thermal operation of a double-circulation recuperator is developed. The use of the described mathematical model of recuperator’s heat work makes it possible to analyze its design in terms of energy efficiency, durability, the ability to reduce heat emissions into the environment.

scholarly journals Numerical Investigation of the Effect of Nanoparticle Diameter and Sphericity on the Thermal Performance of Geothermal Heat Exchanger Using Nanofluid as Heat Transfer Fluid

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1653
Author(s):  
Ruiqing Du ◽  
Dandan Jiang ◽  
Yong Wang
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Heat Transfer Fluid ◽  
Efficiency Coefficient ◽  
Geothermal Heat ◽  
Nanoparticle Diameter ◽  
Geothermal Heat Exchanger

The geothermal heat exchanger system is one of the most energy-efficient and environmentally friendly building service systems. In the present study, CuO/water nanofluid was used as the heat transfer fluid to enhance the energy efficiency of the geothermal heat exchangers. A three-dimensional numerical model was employed to investigate the effect of nanoparticle diameter and sphericity on the thermal performance of the geothermal heat exchanger, and it was well validated against the experimental results of nanofluids in the geothermal heat exchangers. The numerical results showed that nanoparticles with a diameter of 5 nm and 50 nm were not recommended for the nanofluids used in the geothermal heat exchangers due to the performance efficiency coefficient lower than 1, and the optimum diameter was 40 nm, which had the highest performance efficiency coefficient (1.004875). Moreover, the spherical particle-based nanofluid was characterized by the 8.55% higher energy efficiency, in comparison to rod-shaped particle-based nanofluid. Therefore, the application of nanofluid in the geothermal heat exchanger can enhance heat transfer, and the proposed optimum particle diameter and sphericity could contribute to higher energy efficiency.

scholarly journals Identification of heat exchangers according to the criterion of energy efficiency

2019 ◽  
Vol 276 ◽  
pp. 06022 ◽  
Author(s):  
Vladimir Velichkin ◽  
Vladimir Zavyalov
Keyword(s):  
Mathematical Model ◽  
Energy Efficiency ◽  
Mathematical Models ◽  
Control Systems ◽  
Heat Exchangers ◽  
Control Object ◽  
Control Action ◽  
Model Parameters ◽  
Quality Of Control ◽  
The Mathematical Model

The article presents the results of the analysis of the characteristics of heat exchangers methods for determining their mathematical models. The necessity of the availability of the mathematical model during the synthesis of automatic control systems with desired properties. The method of identification of the thermal control object by the testing control action is proposed. Since technological control objects always be an energy of interaction the energy efficiency criterion applied for automatic formation of the control action. Also the analytical self-adjusting system with a reference model in the form of an integrating link was applied. From the analytical researches it follows that the movement of the system along the optimal trajectory occurs at a constant speed and does not depend on the properties of the control object, and the optimal control depends on the properties of the control object, time, and technological requirements. It is shown that mathematical models of heat exchangers of the first and second orders are determined quite simply. The accuracy of the mathematical model parameters is limited only by the accuracy of the experimental data. The quality of control systems with desired properties, synthesized by experimental, and accurate models are virtually indistinguishable.

Experimental Analysis to Optimize the Performance of Air Curtains and Heat Exchangers

2015 ◽  
pp. 590-640
Author(s):  
Samuel Mariano do Nascimento ◽  
Gustavo Galdi Heidinger ◽  
Pedro Dinis Gaspar ◽  
Pedro Dinho Silva
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Environmental Conditions ◽  
Heat Exchangers ◽  
Heat Load ◽  
Experimental Studies ◽  
Air Curtain ◽  
Back Panel

This chapter reports an overview about experimental studies concerning the thermal performance of air curtains and heat exchangers installed in vertical open refrigerated display cases. The air curtain analysis shows the influence on the thermal performance by varying the width of the discharge air grille and the perforation density of the back panel by a mathematical model. The variation on the perforation density of the back panel and the width of discharge air grille alter significantly the thermal entrainment factor and the energy consumption of the equipment. Focusing the influence of environmental conditions on the performance of the heat exchanger, a second mathematical model was developed to evaluate the total heat load, its partial components and the condensate water mass. This analysis provides valuable information to the design of the air curtain and heat exchanger based on in-store environmental conditions and airflow efficiency.

RESEARCH OF INDICATORS OF A VEHICLE WITH A DIESEL WORKING ON DIESEL AND DIESEL GAS CYCLES USING THE MATHEMATICAL MODEL

2020 ◽  
pp. 14-19
Author(s):  
Serhii Kovbasenko ◽  
Andriy Holyk ◽  
Serhii Hutarevych
Keyword(s):  
Mathematical Model ◽  
Diesel Engine ◽  
Environmental Performance ◽  
Energy Performance ◽  
Dual Fuel ◽  
Fuel System ◽  
Compressed Natural Gas ◽  
Diesel Vehicles ◽  
Diesel Cycle ◽  
The Mathematical Model

The features of an advanced mathematical model of motion of a truck with a diesel engine operating on the diesel and diesel gas cycles are presented in the article. As a result of calculations using the mathematical model, a decrease in total mass emissions as a result of carbon monoxide emissions is observed due to a decrease in emissions of nitrogen oxides and emissions of soot in the diesel gas cycle compared to the diesel cycle. The mathematical model of a motion of a truck on a city driving cycle according to GOST 20306-90 allows to study the fuel-economic, environmental and energy indicators of a diesel and diesel gas vehicle. The results of the calculations on the mathematical model will make it possible to conclude on the feasibility of converting diesel vehicles to using compressed natural gas. Object of the study – the fuel-economic, environmental and energy performance diesel engine that runs on dual fuel system using CNG. Purpose of the study – study of changes in fuel, economic, environmental and energy performance of vehicles with diesel engines operating on diesel and diesel gas cycles, according to urban driving cycle modes. Method of the study – calculations on a mathematical model and comparison of results with road tests. Bench and road tests, results of calculations on the mathematical model of motion of a truck with diesel, working on diesel and diesel gas cycles, show the improvement of environmental performance of diesel vehicles during the converting to compressed natural gas in operation. Improvement of environmental performance is obtained mainly through the reduction of soot emissions and nitrogen oxides emissions from diesel gas cycle operations compared to diesel cycle operations. The results of the article can be used to further develop dual fuel system using CNG. Keywords: diesel engine, diesel gas engine, CNG

PUBLIC SUPPORT TO AGRICULTURAL ENERGY RESOURCES AS A MEASURE ENERGY EFFICIENCY IN PROCESSES PRODUCTION OF AGRICULTURAL PRODUCTS

2019 ◽  
pp. 30-44
Author(s):  
Konstantin Igorevich Alekseev ◽  
Andrey Nikolaevich Osipov ◽  
B.O. Hashir ◽  
Elena Nikolaevna Zakharchenko
Keyword(s):  
Energy Efficiency ◽  
Public Support ◽  
Agricultural Products ◽  
Energy Resources

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

scholarly journals Dimensionless Analysis on the Characteristics of Pneumatic Booster Valve with Energy Recovery

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Fan Yang ◽  
Kotaro Tadano ◽  
Gangyan Li ◽  
Toshiharu Kagawa
Keyword(s):  
Mathematical Model ◽  
Energy Efficiency ◽  
Energy Recovery ◽  
Operational Parameters ◽  
Local Pressure ◽  
Air Power ◽  
Improve Energy Efficiency ◽  
Dimensionless Analysis ◽  
Air Supply ◽  
Save Energy

Factories are increasingly reducing their air supply pressures in order to save energy. Hence, there is a growing demand for pneumatic booster valves to overcome the local pressure deficits in modern pneumatic systems. To further improve energy efficiency, a new type of booster valve with energy recovery (BVER) is proposed. The BVER principle is presented in detail, and a dimensionless mathematical model is established based on flow rate, gas state, and energy conservation. The mathematics model was transformed into a dimensionless model by accurately selecting the reference values. Subsequently the dimensionless characteristics of BVER were found. BVER energy efficiency is calculated based on air power. The boost ratio is found to be mainly affected by the operational parameters. Among the structural ones, the recovery/boost chamber area ratio and the sonic conductance of the chambers are the most influential. The boost ratio improves by 15%–25% compared to that of a booster valve without an energy recovery chamber. The efficiency increases by 5%–10% depending on the supply pressure. A mathematical model is validated by experiment, and this research provides a reference for booster valve optimisation and energy saving.

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