scholarly journals Experimental Study of the Variation Dynamic’s for Air Heat Exchanger

2017 ◽  
Vol 9 (3) ◽  
pp. 297-301
Author(s):  
Maryia Marozava ◽  
Dzmitry Hryniuk
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Dynamic Models ◽  
Management Systems ◽  
Stabilization System ◽  
Technological Parameters ◽  
Control Loops ◽  
The Stability

The development of management systems is assigned one of the leading roles. When solving the problems of regulating the technological parameters, various problems arise. One of such problems is the adjustment of control loops. For some control objects, one-time adjustment of the controller parameters can be made, and then it is periodically refined as necessary. In other objects, the changes occur very quickly, but in a certain range. In the latter case, you should first estimate the range of changes. Then find universal robust settings that will ensure the stability and quality of the stabilization system. Some of such objects are air heat exchangers. The article presents the results of the determination of the heat exchanger dynamics. The limits of the variation of the parameters of the dynamic models are determined. There is a significant nonlinearity in the transfer function of the control channel.

THE EFFECT OF LIQUID SUCTION HEAT EXCHANGER SUB-COOLER ON PERFORMANCE OF A FREEZER USING R404A AS WORKING FLUID

2015 ◽  
Vol 76 (11) ◽  
Author(s):  
Muhammad Nuriyadi ◽  
Sumeru Sumeru ◽  
Henry Nasution
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cooling Capacity ◽  
Experimental Results ◽  
Working Fluid ◽  
Liquid Line ◽  
Cabin Temperature

This study presents the effect of liquid-suction heat exchangers (LSHX) sub-cooler in a freezer. The LSHX sub-cooler is a method to increase the cooling capacity of the evaporator by lowering temperature at the condenser outlet. The decrease in temperature of the condenser outlet will cause a decrease in the quality refrigerant entering the evaporator. The lower the quality of the refrigerant entering the evaporator, the higher the cooling capacity produced by the evaporator. The LSHX sub-cooler utilizes a heat exchanger to transfer heat from the outlet of the condenser (liquid line) to the suction of the compressor. In the present study, three different LSHX sub-coolers in the freezer with cabin temperature settings of 0, -10 and -20oC were investigated. The results showed that the lowest and the highest of effectiveness of the heat exchanger were 0.28 and 0.58, respectively. The experimental results also showed that EER reduction is occurred at the cabin temperature setting of 0oC and -10oC, whereas the EER improvements were always occurred at the cabin temperature settings of -20oC.

scholarly journals Determination of main parameters of ISOBUS system based agricultural machinery management

2021 ◽  
Vol 46 (3) ◽  
pp. 40-48
Author(s):  
Magó László ◽  
Kosta Gligorević ◽  
Milan Dražić ◽  
Mićo Oljača
Keyword(s):  
Communication Protocol ◽  
Plant Protection ◽  
Electronic Devices ◽  
Technological Parameters ◽  
Industry Standard ◽  
System Of Parameters ◽  
Agricultural Machines

ISO organization (https://www.iso.org) in early 90s defined an industry standard for the communication protocol among electronic devices of different manufacturers of agricultural machines. After that, all of the market actors recognised that this technology would be very important for agricultural electronics. The appearance of ISOBUS products in the market was in the mid-2000s. ISOBUS description could be found in ISO-11783 (https://www.iso.org). Through the standards and the related technical background, the production processes and the operations could be followed and monitored by the extensive Data Management. Farmers' and users legitimate needs and developing goal is to elaborate a decision support systems that follow-up the utilisation of the machines and ensure the quality of operations. For this purpose, it is essential to determine which technical, economical, technological parameters detection, measurement, transmission, processing, and evaluation becomes necessary. In our work, we reviewed which mechanical characteristic, settings are monitored within the ISOBUS system by the major machine manufacturers. We developed the system of parameters and derived features that provide effective farm-, and land-management in case of attached equipment for spreading of input materials, plant protection and tillage implements.

The issue of "oil shrinkage" during the compounding of oils in the processes of production, collection, preparation and transportation of hydrocarbon raw materials

2021 ◽  
pp. 104-113
Author(s):  
O. P. Deryugina ◽  
E. A. Trapeznikov
Keyword(s):  
Raw Materials ◽  
Raw Material ◽  
Colloidal System ◽  
Main Pipelines ◽  
Different Types ◽  
Preliminary Study ◽  
The Stability ◽  
Mixed Oil

The article discusses the issue of industrial compounding, which improves the quality of the raw materials supplied to the main pipelines. Compounding from "to compound" (English) - to mix. When mixing different types of oil obtained, "incompatibility" is possible, which is expressed in the precipitation of a solid sediment and violation of the stability of the colloidal system and due to the differing properties of oils. Attention to this problem is due to the tightening of requirements for the quality of raw materials that must comply with modern standards. The article discusses the causes of the problem of "incompatibility" of oil during compounding and effective ways of solving it, substantiates the need for a preliminary study of the properties of mixed oil in order to identify possible incompatibility of various types of oil. The standard tests for determination of incompatibility indices characterizing the ability of raw materials to mix are considered. The article substantiates the need to develop methods for diagnosing the incompatibility of oils as the most important task of modern chemical science, the solution of which will improve the quality of the raw material obtained and solve many technological problems in the compounding process.

Dynamic Analysis and Stability Improvement Concerning the Integration of Wind Farms Kurdistan Electric Network Case Study

2011 ◽  
pp. 198-219 ◽  
Author(s):  
Mohammad Saleh ◽  
Hassan Bevrani
Keyword(s):  
Wind Power ◽  
Dynamic Models ◽  
Wind Farms ◽  
Integrated System ◽  
Electric Network ◽  
Control Approach ◽  
Control Loops ◽  
And Performance ◽  
The Stability

This chapter presents an overview of key issues and technical challenges in a regional electric network, following the integration of a considerable amount of wind power. A brief survey on wind power system, the present status of wind energy worldwide, common dynamic models, and control loops for wind turbines are given. In this chapter, the Kurdistan electric network in the Northwest part of Iran is introduced as a case study system, and an analytical approach is conducted to evaluate the potential of wind power installation, overall capacity estimation, and economic issues, based on the practical data. Then, the impact of high penetration wind power on the system dynamic and performance for various wind turbine technologies is presented. The stability of integrated system is analyzed, and the need for revising of conventional controls and performance standards is emphasized. Finally, a STATCOM-based control approach is addressed to improve the system stability.

scholarly journals Research on the relative productivity of a drum mill type SAG 8.5×5.3

2020 ◽  
Vol 168 ◽  
pp. 00012
Author(s):  
Ivan Minin
Keyword(s):  
Energy Consumption ◽  
Control Parameters ◽  
Operational Mode ◽  
Operational Parameters ◽  
Technological Parameters ◽  
Expected Performance ◽  
Relative Productivity ◽  
Required Quality

The determination of the optimal operational mode of drum mills can be assessed by different criteria. The most important of them can be formulated as follows: “To be specified and established the values of the mill operational parameters regarding to which it is possible to be provided the user’s expected performance at the required quality of the final product and the same to be achieved at minimal energy consumption”. For the fulfillment of this condition, there has to be determined the laws of productivity variation, the final product quality and the energy consumption in function of the adequately chosen representative control parameters of the mill. There are obtained mathematical models, describing the most important technological parameters of the machine and are made conclusions about the factors influencing on them.

What is the Best Solution to Improve Thermal Performance of Storage Tanks With Immersed Heat Exchangers: Baffles or a Divided Tank?

2008 ◽  
Author(s):  
Aaron D. Wade ◽  
Jane H. Davidson ◽  
Julia F. Haltiwanger
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
Thermal Stratification ◽  
Storage Tanks ◽  
Stored Energy ◽  
Tubular Heat Exchanger ◽  
Energy Delivery ◽  
Potential Methods

Prior studies of indirect water storage tanks that employ an immersed heat exchanger to discharge the stored energy have identified two potential methods of improving the rate of energy extraction: 1) an internal baffle to increase the velocity across the heat exchanger, and 2) a divided storage compartment to achieve thermal stratification. Thermal performance of these two options is compared to that of a conventional cylindrical tank during transient discharge. Each tank has a storage volume of 350 liters and a 10 m long, 0.3 m2 coiled tubular heat exchanger. For the specific configurations evaluated, the baffled heat exchanger provides the highest energy delivery rates and heat exchanger outlet temperatures. An analytic model shows the advantage of the divided storage depends on the NTU of the immersed heat exchanger. The heat exchanger employed in the present study is too small to realize the potential benefit of a divided storage. Both options, if used in the appropriate system, can improve thermal performance as measured by the rate and quality of delivered energy. The baffle is most appropriate when storage-side natural convection is the largest thermal resistance of the heat exchanger. The divided tank is useful when the NTU of the heat exchanger exceeds three.

Finite Element Analysis for the Stiffness and the Buckling of Corrugated Tubes in Heat Exchanger

2012 ◽  
Vol 468-471 ◽  
pp. 1675-1680 ◽  
Author(s):  
Xiao Jing Wang ◽  
Zhi Min Wang ◽  
Nian Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stability Analysis ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
External Pressure ◽  
Element Analysis ◽  
Value Analysis ◽  
Compressive Pressure ◽  
The Stability

Corrugated tubes in a heat exchanger are analyzed by using the FEA methods. And the formula how to compute single wave’s rigidity is obtained. Besides, methods of analyzing the stability of corrugated tubes under internal compressive pressure and external pressure are proposed which include characteristic value analysis and non-linear stability analysis, thus providing theory basis for the stability research of heat exchangers.

scholarly journals The Influence of Different Assist Gases on Ductile Cast Iron Cutting by CO2 Laser

2017 ◽  
Vol 17 (4) ◽  
pp. 109-114 ◽  
Author(s):  
J. Meško ◽  
R. Nigrovič ◽  
A. Zrak
Keyword(s):  
Cast Iron ◽  
Laser Cutting ◽  
Roughness Parameter ◽  
Cutting Speed ◽  
Nodular Cast Iron ◽  
Ductile Cast Iron ◽  
Engineering Practice ◽  
Technological Parameters ◽  
The Stability

Abstract This article deals with the technology and principles of the laser cutting of ductile cast iron. The properties of the CO2 laser beam, input parameters of the laser cutting, assist gases, the interaction of cut material and the stability of cutting process are described. The commonly used material (nodular cast iron - share of about 25% of all castings on the market) and the method of the laser cutting of that material, including the technological parameters that influence the cutting edge, are characterized. Next, the application and use of this method in mechanical engineering practice is described, focusing on fixing and renovation of mechanical components such as removing the inflow gate from castings with the desired quality of the cut, without the further using of the chip machining technology. Experimental samples from the nodular cast iron were created by using different technological parameters of laser cutting. The heat affected zone (HAZ), its width, microstructure and roughness parameter Pt was monitored on the experimental samples (of thickness t = 13 mm). The technological parameters that were varied during the experiments included the type of assist gases (N2 and O2), to be more specific the ratio of gases, and the cutting speed, which ranged from 1.6 m/min to 0.32 m/min. Both parameters were changed until the desired properties were achieved.

Deflections of A Multipass Shell-and-Tube Heat Exchanger Bolted Joint Subjected to Nonaxisymmetric Thermal Loading

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Natalia Petrova ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermal Loading ◽  
Cocurrent Flow ◽  
Finite Element Models ◽  
Bolted Joint ◽  
Tube Heat Exchanger ◽  
Specific Geometry ◽  
Shell And Tube

Despite the fact that multipass shell-and-tube heat exchangers operating at high temperature are subject to frequent problems related to flange sealing, there is neither detailed explanations for the reasons of the failures nor an adequate solution to this problem. Specific geometry of multipass heat exchangers and the temperature difference between the inlet and the outlet fluids is responsible for the existence of a thermal circumferential gradient at the shell-to-channel bolted joint. However, existing flange design methods do not address nonaxisymmetrical temperature loading of the flanged joint assembly. The circumferential thermal gradient, as the cause of frequent failures to seal the flanged joints, is ignored. This paper outlines the analytical modeling of a flanged joint with a tube sheet of a multipass heat exchanger subjected to a nonaxisymmetrical thermal loading. A shell-and-tube heat exchanger of 51 in. diameter with cocurrent flow was used for analysis. The main steps of the theoretical analysis used for the determination of the circumferential temperature profiles and the thermal expansion displacements and distortions of the bolted joint components are given. The results from the proposed analytical model are compared with those obtained from finite element models.

scholarly journals METHODOLOGY FOR AUTOMATIC DETERMINATION OF CONTRAST OF LASER MARKING FOR DIFFERENT MATERIALS

2019 ◽  
Vol 3 ◽  
pp. 134
Author(s):  
Lyubomir Lazov ◽  
Edmunds Teirumnieks ◽  
Nikolay Angelov ◽  
Erika Teirumnieka
Keyword(s):  
Laser System ◽  
Digital Camera ◽  
Test Field ◽  
Automatic Determination ◽  
Technological Parameters ◽  
Test Analysis ◽  
Laser Marking ◽  
Different Types

A new methodology for determining and optimizing the contrast of the technological laser marking process has been developed. It can evaluate the quality of the markings regardless of the type of material and the type of laser system. To perform the test analysis, a specialized test field is programmed, which including the change of two of the main parameters influencing the marking process: the linear energy density (LED) and the linear density of the pulses (LDI). Marking of a test field consisting of squares of a certain size is done by means of a raster marking method with a constant step between the lines. The results are processed with a digital camera and specialized software. The maximum blackening is compared with the background of all fields and is juxtaposed with the effective energy needed to obtain a certain contrast. Several consecutive iterations are made, with each of the following experiments excluding the variants with least contrast. Thus, the study consistently brings the result to a minimum working area of the basic technological parameters, providing the user's desired contrast of the marking. The developed author's method of automatically determining the contrast of the laser marking reduces the time for preliminary experimental research and gives a reliable and subjectively absent way of qualitatively marking different types of industrial products.

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