Compulsory heat exchange between the heat carrier and bread when moistening air in the baking camera

2019 ◽  
Vol 28 (1) ◽  
pp. 44-48
Author(s):  
S.A. Romanchikov ◽  
Keyword(s):  
1984 ◽  
Vol 46 (2) ◽  
pp. 130-133
Author(s):  
A. A. Mikhalevich ◽  
V. A. Nemtsev ◽  
V. I. Nikolaev ◽  
L. N. Shegidevich

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Cheng Li ◽  
Wei-Jun Zhang ◽  
Zhi Yi ◽  
Na Li ◽  
Kai Li

Intermediate heat carriers have been applied in engineering as enhanced heat transfer elements, but their theoretical analysis still needs to be improved. Therefore, an intermediate heat carrier is added to establish the quaternary model of the furnace gas under nongray radiation characteristics. Based on this model, an analytical expression of heat flux on the surface of the billet is derived. General rule of the impact of intermediate heat carrier on the thermal efficiency in the furnace can be properly derived by analytical calculation from a theoretical point of view. The results show that the longer the length of the intermediate heat carrier located at the top of the furnace, the greater the heat exchange capacity on the surface of the billet. Meanwhile, when the intermediate heat carrier is located in the center of the furnace top, the billet gets higher heat flux; the closer to both sides, the lower the heat flux. In addition, the influence that the surface emissivity of the intermediate heat carrier has on the heat transfer of the billet surface is related to the values of εg and αgw. Comparison with previous literature shows that adding intermediate heat carrier can improve the heat exchange capacity of billet.


2020 ◽  
Vol 22 (4) ◽  
pp. 82-93
Author(s):  
Roman Chernukhin ◽  
◽  
Aleksey Dolgushin ◽  
Nikolai Kasimov ◽  
Vladimir Ivancivsky ◽  
...  

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.


Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3492
Author(s):  
Valeriy Nikolsky ◽  
Ivan Kuzyayev ◽  
Roman Dychkovskyi ◽  
Oleksandr Alieksandrov ◽  
Vadim Yaris ◽  
...  

The effect of basic parameters of the channels of disk pulse devices on the heat exchange efficiency was studied both analytically and experimentally, especially in terms of pulse acting on the heat carrier. A methodology to determine the main parameters, namely the pressure and the temperature of the heat carrier as well as the pulse effect on the fluid, was proposed. The mathematical models of the effect of the structural and technological parameters of the channels in the disk pulse device on the heat exchange efficiency were developed. The models’ adequacy was proved based on a series of experimental studies involving devices with one-stage and multistage systems of pulsed heat carrier processing. This enabled the development, testing, and implementation of practical construction designs of pulse disk heat generators for decentralized heating of commercial and domestic buildings with one-stage and multistage systems of pulsed heat carrier processing. Taking into account the results of the mathematical modeling, the developed method of multistage pulse action was proved experimentally and implemented in regard to the structural design of a working chamber of the disk pulse heat generator. An efficient geometry of the working chamber of the disk pulse heat generator was specified for its further integration into the system of decentralized heat supply. One of the developed heat generators with the multistage pulse action on the heat carrier was integrated into the heating system of a greenhouse complex with a 0.86–0.9 efficiency coefficient.


Author(s):  
Volodymyr Kravchenko ◽  
Oleksandr Lymarenko ◽  
Zhou Xiaolong ◽  
Kiril Khromiy ◽  
Yehor Buchka

Today, the world oversees an explosive development of the nuclear power stations (NPS) of a low power. Most projects deal with pressurized water reactors and as a matter of fact with steam generators (SG). Ukraine has a well-developed engineering industry backbone that can be used for the production of the equipment required for the nuclear power plants of a low power. This scientific paper delves into the computations of the strength of elements used for the monotube steam generator with cylindrical coils that is the most presentable of all the projects in question in IAEA materials. Appropriate methods were developed to perform structural computations and steam generator strength computations. The mathematical model was developed that allows us to perform strength computations of the SG elements making use of the analytical method with reference to the Regulations and do simulations using the ANSYS software code. The specified elements include the body elements, in particular the cylindrical part, the flange, the bottom and the cover, including the heat carrier branch pipe and heat exchange tubes. The comparison of the data obtained by both methods showed their similarity and accordingly, the accuracy of the data that are indicative of the need for an increase in the wall thickness of the cylindrical part of the external branch pipe intended for the heat carrier. The body bottom strain for calculated dimensions exceeds the permissible value by 1.56 %. Since this value is 5 % lower than permissible values it is deemed that the strength condition is passed through. The simulation proved that the strength conditions are met for heat exchange tubes, for the body, the body cover, the body flange, the conical part of the external branch pipe intended for the heat carrier. Based on the analysis done, we would like to recommend performing strength computations using the normative method with the subsequent check out by the simulation using the computer code.


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