A Computer Code Using Exergy for Optimizing Thermal Plants

1991 ◽  
Vol 113 (1) ◽  
pp. 145-150 ◽  
Author(s):  
G. Bidini ◽  
S. S. Stecco
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Temperature Difference ◽  
Computer Code ◽  
Heat Transfer Surface ◽  
Exergetic Efficiency ◽  
Industrial Plants ◽  
Exergetic Analysis ◽  
Reducing Energy

This paper presents an exergetic approach to reducing energy consumption in industrial plants. The minimum pinchpoint temperature difference is determined for several cases of heat exchange between hot and cold fluid streams with reduced thermal losses. The proposed method, designated TEXAS (Thermal and economic EXergetic Analysis of Systems), derives families of characteristic curves showing economic parameters versus exergetic efficiency in relation to factors such as heat transfer, surface, and scaling. As the method is highly affected by the economic parameter assumptions, the sensitivity of the variations in the parameters is also analyzed.

Heat exchange of dynamic powder beds with a heat-transfer surface. II. A dust-laden gas flow

1999 ◽  
Vol 72 (1) ◽  
pp. 7-10
Author(s):  
D. S. Pashkevich ◽  
V. N. Krasnokutskii ◽  
V. B. Petrov ◽  
V. L. Korolev
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Gas Flow ◽  
Heat Transfer Surface

scholarly journals Research on Heat Transfer Performance of Micro-Channel Backplane Heat Pipe Air Conditioning System in Data Center

2020 ◽  
Vol 10 (2) ◽  
pp. 583
Author(s):  
Liping Zeng ◽  
Xing Liu ◽  
Quan Zhang ◽  
Jun Yi ◽  
Xianglong Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Pipe ◽  
Temperature Difference ◽  
Air Conditioning ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Micro Channel ◽  
Filling Rate ◽  
Air Conditioning System

This paper deals with the heat transfer performance of a micro-channel backplane heat pipe air conditioning system. The optimal range of the filling rate of a micro-channel backplane heat pipe air conditioning system was determined in the range of 65–75%, almost free from the interference of working conditions. Then, the influence of temperature and air volume flow rate on the heat exchange system were studied. The system maximum heat exchange is 7000–8000 W, and the temperature difference between the inlet and outlet of the evaporator and the condenser is almost 0 °C. Under the optimum refrigerant filling rate, the heat transfer of the micro-channel heat pipe backplane system is approximately linear with the temperature difference between the inlet air temperature of the evaporator and the cooling distribution unit (CDU) inlet water temperature in the range of 18–28 °C. The last part compares the heat transfer characteristics of two refrigerants at different filling rates. The heat transfer, pressure, and refrigerant temperature of R134a and R22 are the same with the change of filling rate, but the heat transfer of R134a is lower than that of R22. The results are of great significance for the operational control and practical application of a backplane heat pipe system.

Mechanisms of Heat Transfer Enhancement of Gas–Solid Fluidized Bed: Estimation of Direct Contact Heat Exchange From Heat Transfer Surface to Fluidized Particles Using an Optical Visualization Technique

1995 ◽  
Vol 117 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Y. Kurosaki ◽  
I. Satoh ◽  
T. Ishize
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Fluidized Bed ◽  
Flow Rate ◽  
Direct Contact ◽  
Heat Transfer Surface ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Contact Frequency ◽  
Fluidized Particles

This paper deals with mechanisms of heat transfer in a gas–solid fluidized bed. Heat transfer due to heat exchange by direct contact from a heat transfer tube immersed in the bed to fluidized particles was studied by means of visualization of contact of the fluidized particles to the heat transfer surface. The results show that the duration of contact of fluidized particles was almost uniform over the tube circumference and was hardly affected by the flow rate of fluidizing gas. On the other hand, the contact frequency between the particles and heat transfer tube was evidently influenced by the gas flow rate and particles diameter, as well as the location on the tube circumference. Using the visualized results, the amount of heat conducted to fluidized particles during the contact was estimated. This result showed that unsteady heat conduction to the fluidized particles plays an important role in the heat transfer, especially at the condition of incipient fluidization.

scholarly journals Specification of Glazings for Façades Based on Spectrophotometric Characterization of Transmittance

2021 ◽  
Vol 13 (10) ◽  
pp. 5437
Author(s):  
Helenice Maria Sacht ◽  
Luís Bragança ◽  
Manuela Almeida ◽  
Rosana Caram
Keyword(s):  
Heat Transfer ◽  
Optical Properties ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Thermal Performance ◽  
Near Infrared ◽  
Temperate Climate ◽  
Solar Control ◽  
Indoor Spaces

The correct specification of glazings for façades can reduce the energy consumption in buildings. The heat exchange occurs through transparent surfaces and radiation reaches the building as light and heat. Therefore, glazings significantly contribute to the heat transfer between outdoor and indoor spaces and act directly on daylighting and thermal comfort. This paper reports on the spectrophotometric characterization of glazings transmittance for the study of components of a modular façade system and its suitability for the climate of Portugal (temperate climate). The study focused on results of spectrophotometric measurements of optical properties, specifically the transmittance of some types of glazings (solar control, self-cleaning, low-e, float, and extra-clear) and two types of double glazings. The results show the percentage of transmission to ultraviolet, visible, and near-infrared regions and its importance, which enabled the analysis of the glazing efficiency regarding daylighting and the correlation to thermal performance. Subsidies and indications for the specification and adequate uses of transparent surfaces have been presented and complemented the datasheets available from the manufactures.

scholarly journals INTENSIFICATION OF HEAT EXCHANGE IN DIABATIC RECTIFICATION COLUMNS

2020 ◽  
pp. 511-518
Author(s):  
Nikolay Aleksandrovich Voinov ◽  
Denis Andreyevich Zemtsov ◽  
Anastasiya Viktorovna Bogatkova ◽  
Nina Vladimirovna Deryagina
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Film Flow ◽  
Heat Removal ◽  
Heat Transfer Surface ◽  
Water Mixture ◽  
Gravitational Flow ◽  
Intensification Of Heat Exchange ◽  
The Cost ◽  
Intensify Heat Transfer

The heat exchange in a diabatic column was investigated during the rectification of an ethanol-water mixture, in which partial condensation of rising vapors on the surface of vertical heat exchange tubes installed vertically along the height of the installation was carried out, as well as the evaporation of intermediate condensate on the surface of horizontal plates. Based on the review of diabatic columns, it is shown that they can reduce the cost of conducting the rectification process. Heat-exchange devices placed on trays of rectification units are considered and ways to intensify heat transfer in them are proposed. It has been established that the most efficient heat removal in heat exchangers of diabatic columns is achieved when using a film flow of a coolant on a heat transfer surface. Heat transfer in a diabatic column is investigated during gravitational flow of surfaces of heat exchange tubes, as well as when organizing an ascending and descending co-current film flow, both in the case of heating and boiling of the coolant. To intensify heat transfer in the coolant film, a helical artificial roughness was installed on the surface of the pipes, made in the form of a wire spiral tightly mounted on the heat transfer surface. The geometric parameters of the helical roughness, such as the distance between the turns of the spiral and the height of the wire, which have the greatest influence on the intensity of heat transfer, have been established. Dependences for determining the value of the heat transfer coefficient are presented and an estimate of the value of the specific heat flux in the diabatic column is given.

scholarly journals Study by the numerical method of increasing the efficiency of falling ventilation jets for a channel compact air conditioning system

2020 ◽  
Vol 17 (6) ◽  
pp. 164-170
Author(s):  
V. R. Taurit ◽  
◽  
I. I. Sukhanova ◽  
A. N. Kolosnitsyn ◽  
◽  
...  
Keyword(s):  
Energy Consumption ◽  
Numerical Method ◽  
Temperature Difference ◽  
Air Conditioning ◽  
Initial Temperature ◽  
Air Conditioning System ◽  
Air Conditioning Systems ◽  
Reducing Energy

The problem of significantly reducing the consumption of ventilation air in ducted air conditioning systems by optimizing the efficiency of the air distributor is solved. Unconventional falling non-isothermal jets are experimentally investigated by numerical method with the identification of the structure features and determination of the calculated coefficients m and n according to the proposed methodology. The possibilities of reducing energy consumption by increasing the initial temperature difference of the supply duct air are shown.

Exergy analysis of ethylbenzene dehydrogenation to styrene monomer

2018 ◽  
Vol 29 (7) ◽  
pp. 1098-1115 ◽  
Author(s):  
Ahmad Taghizadeh Damanabi ◽  
Fatemeh Bahadori
Keyword(s):  
Energy Consumption ◽  
Exergy Analysis ◽  
High Energy ◽  
Injection Rate ◽  
Exergetic Efficiency ◽  
Oxygen Injection ◽  
Styrene Monomer ◽  
Ethylbenzene Dehydrogenation ◽  
Benzene Toluene ◽  
Exergetic Analysis

In this paper, exergetic analysis for dehydrogenation of ethylbenzene over a potassium-promoted iron oxide catalyst for styrene monomer production is investigated. The purpose of the study is to decrease the work loss in the process. Due to the high energy consumption of the unit, exergy analysis was used to optimize the energy consumption of styrene production unit and associated fractionation unit. Preheater, second reactor, and benzene–toluene tower were studied to optimize energy consumption. It is observed that coupling of an Liquified Natural Gas (LNG) type of heat exchanger with preheater improves the exergetic efficiency of the preheater. Also, decreasing the pressure of benzene–toluene column from 220 kPa to 60 kPa increases the exergetic efficiency from 77.45 to 90.86, while by optimizing the oxygen injection rate to the second reactor, the exergetic efficiency increased from 25.76 to 38.07.

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