High-Temperature Heat Transfer Agents

1975 ◽  
pp. 696-704
Author(s):  
N. B. Vargaftik
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Temperature Heat ◽  
Transfer Agents

EFFICIENCY OF MULTI-LEVEL ROTARY THERMAL STERILIZATION OF PEAR COMPOTE IN A CONTAINER SKO 1-82-1000 INOPEN-TYPE APPARATUSES WITH THE USE OF LIQUID HIGH-TEMPERATURE HEAT TRANSFER AGENTS

2021 ◽  
Author(s):  
М.М. РАХМАНОВА ◽  
А.Ф. ДЕМИРОВА ◽  
М.Э. АХМЕДОВ ◽  
Ю.Ф. РОСЛЯКОВ ◽  
Г.И. КАСЬЯНОВ
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Wall Layer ◽  
Temperature Heat ◽  
Step Heating ◽  
Standard Value ◽  
Multi Level ◽  
First Time ◽  
Sterilization Mode ◽  
Transfer Agents

Разработан новый режим многоуровневой стерилизации компота из груш в стеклотаре СКО 1-82-1000 с использованием жидких высокотемпературных теплоносителей, сущность которого заключается в том, что ступенчатый нагрев осуществляется последовательно в воде и растворе диметилсульфоксида с последующим ступенчатым охлаждением в воде с перепадом температур до 20–25°С. Впервые при разработке новых режимов стерилизации введен коэффициент промышленной стерильности Пст, определяемый отношением фактического значения стерилизующего эффекта разработанного режима к нормативному, обеспечивающему промышленную стерильность продукции. Для разработанного стерилизационного режима коэффициент промышленной стерильности с учетом нормативного значения стерилизующего эффекта для компотов, равного 150–200 усл. мин, составляет для пристеночного слоя Пст = 220/200 = 1,1; для центрального слоя Пст = 207/200 = 1,03. Оба значения коэффициента промышленной стерильности приближаются к единице, что говорит об отсутствии перегрева отдельных слоев продукта, характерного для традиционных стерилизационных режимов. Многоуровневый стерилизационный режим способствует снижению длительности термообработки, превышающей 60 мин, при обеспечении требуемого уровня безопасности продукции. A new method of multi-level sterilization of compote from pears in glass containers SKO 1-82-1000 with the use of liquid high-temperature heat transfer agents, the essence of which is that the step heating is carried out sequentially in water and a solution of dimethyl sulfoxide, followed by step cooling in water with a temperature difference of up to 20–25°C. For the first time in the development of new sterilization regimes, the coefficient of industrial sterility was introduced, which is determined by the ratio of the actual value of the sterilizing effect of the developed regime to the standard one that ensures industrial sterility of products. For the developed sterilization mode, the coefficient of industrial sterility, taking into account the standard value of the sterilizing effect for compotes, equal to 150–200 conditional minutes, is for the wall layer Pst = 220/200 = 1,1; for the central layer Pst = 207/200 = 1,03. Both values of the industrial sterility coefficient approach one, which indicates the absence of overheating of individual layers of the product, which is typical for traditional sterilization modes. Multi-level sterilization mode helps to reduce the duration of heat treatment, exceeding 60 minutes, while ensuring the required level of product safety.

Effect of Absorptive Coating of the Hot Fluid Passage of a Heat Exchanger Employing Exergy-Optimized Pin Fins in High Temperature Applications

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Nwosu P. Nwachukwu ◽  
Samuel O. Onyegegbu
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Simple Relation ◽  
Base Temperature ◽  
Minimum Entropy ◽  
Pin Fin ◽  
Temperature Heat ◽  
Pin Fins ◽  
Minimum Entropy Generation ◽  
Fluid Parameters

An expression for the optimum pin fin dimension is derived on exergy basis for a high temperature exchanger employing pin fins. The present result differs from that obtained by Poulikakos and Bejan (1982, “Fin Geometry for Minimum Entropy Generation in Forced Convection,” ASME J. Heat Transfer, 104, pp. 616–623) for a low temperature heat recovery application. Also, a simple relation is established between the amounts the base temperature of the optimized pin fin is raised for a range of absorptive coating values. Employing this relation, if the absorptivity of the coating, the plate emissivity, the number of protruding fins, and some area and fluid parameters are known, the corresponding value for the base temperature of the fin is immediately obtained. The analysis shows that the thermal performance of the exchanger improves substantially with a high absorptivity coating hence can be seen as a heat transfer enhancement feature of the exchanger operating with radiation dominance.

Suppression of the Sonic Heat Transfer Limit in High-Temperature Heat Pipes

1989 ◽  
Vol 111 (3) ◽  
pp. 605-610 ◽  
Author(s):  
Flavio Dobran
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Pipes ◽  
Vapor Flow ◽  
Transport Capacity ◽  
Flow Area ◽  
Temperature Heat ◽  
Liquid Evaporation ◽  
Heat Transfer Limit ◽  
Axial Heat

The design of high-performance heat pipes requires optimization of heat transfer surfaces and liquid and vapor flow channels to suppress the heat transfer operating limits. In the paper an analytical model of the vapor flow in high-temperature heat pipes is presented, showing that the axial heat transport capacity limited by the sonic heat transfer limit depends on the working fluid, vapor flow area, manner of liquid evaporation into the vapor core of the evaporator, and lengths of the evaporator and adiabatic regions. Limited comparisons of the model predictions with data of the sonic heat transfer limits are shown to be very reasonable, giving credibility to the proposed analytical approach to determine the effect of various parameters on the axial heat transport capacity. Large axial heat transfer rates can be achieved with large vapor flow cross-sectional areas, small lengths of evaporator and adiabatic regions or a vapor flow area increase in these regions, and liquid evaporation in the evaporator normal to the main flow.

Fluidized-Bed Heat Transfer Modeling for the Development of Particle/Supercritical-CO2 Heat Exchanger

2017 ◽  
Author(s):  
Zhiwen Ma ◽  
Janna Martinek
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Solid Particles ◽  
Heat Transfer Modeling ◽  
Power Cycle ◽  
Heat Exchanger Design ◽  
Temperature Heat ◽  
The Cost

Concentrating solar power (CSP) technology is moving toward high-temperature and high-performance design. One technology approach is to explore high-temperature heat-transfer fluids and storage, integrated with a high-efficiency power cycle such as the supercritical carbon dioxide (s-CO2) Brayton power cycle. The s-CO2 Brayton power system has great potential to enable the future CSP system to achieve high solar-to-electricity conversion efficiency and to reduce the cost of power generation. Solid particles have been proposed as a possible high-temperature heat-transfer medium that is inexpensive and stable at high temperatures above 1,000°C. The particle/heat exchanger provides a connection between the particles and s-CO2 fluid in the emerging s-CO2 power cycles in order to meet CSP power-cycle performance targets of 50% thermal-to-electric efficiency, and dry cooling at an ambient temperature of 40°C. The development goals for a particle/s-CO2 heat exchanger are to heat s-CO2 to ≥720°C and to use direct thermal storage with low-cost, stable solid particles. This paper presents heat-transfer modeling to inform the particle/s-CO2 heat-exchanger design and assess design tradeoffs. The heat-transfer process was modeled based on a particle/s-CO2 counterflow configuration. Empirical heat-transfer correlations for the fluidized bed and s-CO2 were used in calculating the heat-transfer area and optimizing the tube layout. A 2-D computational fluid-dynamics simulation was applied for particle distribution and fluidization characterization. The operating conditions were studied from the heat-transfer analysis, and cost was estimated from the sizing of the heat exchanger. The paper shows the path in achieving the cost and performance objectives for a heat-exchanger design.

scholarly journals Use of Low-Temperature Heat Transfer Agents in the Work of Heat Pumps in Sub-zero Temperatures Conditions

2019 ◽  
Vol 157 ◽  
pp. 1456-1461
Author(s):  
Alexey N. Vasiliev ◽  
Olga V. Shepovalova ◽  
Evgenia V. Tutunina
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Pumps ◽  
Temperature Heat ◽  
Transfer Agents
Sign in / Sign up

Export Citation Format

Share Document