scholarly journals Parameters of the plain weave meshfor the nozzle of a regenerative heat exchanger

2021 ◽  
pp. 9-15
Author(s):  
Yaroslav Dvoinos ◽  
Pavlo Yevziutin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Hydraulic Resistance ◽  
Wire Mesh ◽  
Simulation Experiments ◽  
Regenerative Heat ◽  
Plain Weave ◽  
The Heat Transfer Coefficient

Regenerative heat exchangers have disadvantages such as low heat transfer coefficient from the nozzle to the gas and high hydraulic resistance due to the design of the nozzles. Wire-mesh nozzles can eliminate these shortcomings of regenerators. Wire-mesh nozzles have low hydraulic resistance and large heat transfer surface. The process of heat and mass transfer in a regenerative heat exchanger is considered. A series of numerical simulation experiments was performed. Theoretically, the optimal configuration of the nozzle was calculated: a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm. The operational modes for the regenerator are considered, taking into account the period for drying the nozzle from moisture and the maximum mass of water that can hold the nozzle without the formation of drops. Given the condensation of moisture on the nozzle, the following assumptions are made: There is no temperature and concentration inhomogeneity in the cross section of the regenerator channel; The effect of thermal conductivity in the axial direction in contact between the nozzle elements on the temperature profile of the nozzle is insignificant; The time over which the regenerator is operated between the nozzle drying periods is quite short, and the thickness of the condensate layer does not affect the hydrodynamic mode of the heat regeneration process and the value of the heat transfer coefficient. The duration of the cooling and drying period depends on the humidity of the inlet air and the area of the nozzle. This is due to the need to prevent the accumulation of moisture in the device, which can lead to the reproduction of harmful bacteria and contamination of the nozzle. In the SolidWorks Flow Simulation application, simulation experiments were performed for a regenerator model accounting for the influence of compressed air motion resulting from grouped location of the nozzle elements, and the results are shown in the figures. Comparison of the results from analytical calculations and simulation experiments showed the efficiency of the mathematical model and the possibility of its use in the design calculation of regenerators. Correlation dependences have been established to determine the heat transfer coefficient and hydraulic resistance depending on the hydrodynamic conditions. The mathematical and physical model taking into account the condensation of moisture on the nozzle has been specified. Calculations have been performed for the optimal nozzle made in the form of a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm.

scholarly journals DEVELOPMENT OF HIGH EFFICIENT SHELL-AND-TUBE HEAT EXCHANGERS BASED ON PROFILED TUBES

2020 ◽  
Author(s):  
Djamalutdin Chalaev ◽  
◽  
Nina Silnyagina ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Hydraulic Resistance ◽  
Heat Exchangers ◽  
Experimental Studies ◽  
Corrugated Tube ◽  
The Heat Transfer Coefficient

The use of advanced heat transfer surfaces (corrugated tubes of various modifications) is an effective way to intensify the heat transfer and improve the hydraulic characteristics of tubular heat exchangers. The methods for evaluating the use of such surfaces as working elements in tubular heat exchangers have not been developed so far. The thermal and hydrodynamic processes occurring in the tubes with the developed surfaces were studied to evaluate the efficiency of heat exchange therein. Thin-walled corrugated flexible stainless steel tubes of various modifications were used in experimental studies. The researches were carried out on a laboratory stand, which was designed as a heat exchanger type "tube in tube" with a corrugated inner tube. The stand was equipped with sensors to measure the thermal hydraulic flow conditions. The comparative analysis of operation modes of the heat exchanger with a corrugated inner tube of various modifications and the heat exchanger with a smooth inner tube was performed according to the obtained data. Materials and methods. A convective component of the heat transfer coefficient of corrugated tube increased significantly at identical flow conditions comparing with a smooth tube. Increasing the heat transfer coefficient was in the range of 2.0 to 2.6, and increased with increasing Reynolds number. The increase in heat transfer of specified range outstripped the gain of hydraulic resistance caused by increase of the flow. Results and discussion. CFD model in the software ANSYS CFX 14.5 was adapted to estimate the effect of the tube geometry on the intensity of the heat transfer process. A two-dimensional axially symmetric computer model was used for the calculation. The model is based on Reynolds equation (Navier-Stokes equations for turbulent flow), the continuity equation and the energy equation supplemented by the conditions of uniqueness. SST-turbulence model was used for the solution of the equations. The problem was solved in the conjugate formulation, which allowed assessing the efficiency of heat exchange, depending on various parameters (coolant temperature, coolant velocity, pressure). The criteria dependences were obtained Nu = f (Re, Pr). Conclusions. The use a corrugated tube as a working element in tubular heat exchangers can improve the heat transfer coefficient of 2.0 - 2.6 times, with an increase in hydraulic resistance in the heat exchanger of 2 times (compared with the use of smooth tubes). The criteria dependences obtained on the basis of experimental studies and mathematical modeling allow developing a methodology for engineering calculations for the design of new efficient heat exchangers with corrugated tubes.

Test and Analysis on the Heat Transfer Coefficient of the Mixed Plate Heat Exchanger

2014 ◽  
Vol 552 ◽  
pp. 55-60
Author(s):  
Zheng Ming Tong ◽  
Peng Hou ◽  
Gui Hua Qin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Mixed Mode ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Fitting Method ◽  
Engineering Significance ◽  
The Heat Transfer Coefficient

In this article, we use BR0.3 type plate heat exchanger for experiment,and the heat transfer coefficient of the mixed plate heat exchanger is explored. Through the test platform of plate heat exchanger, a large number of experiments have been done in different mixed mode but the same passageway,and lots experimental data are obtained. By the linear fitting method and the analysis of the data, the main factors which influence the heat transfer coefficient of mixed plate heat exchanger were carried out,and the formula of heat transfer coefficient which fits at any mixed mode plate heat exchanger is obtained, to solve the problem of engineering calculation.The fact , there is no denying that the result which we get has great engineering significance

Experimental Study on Integrated Performance for Flower Baffle Heat Exchanger’s Distance between Two Flower Baffles

2010 ◽  
Vol 29-32 ◽  
pp. 132-137 ◽  
Author(s):  
Xue Jiang Lai ◽  
Rui Li ◽  
Yong Dai ◽  
Su Yi Huang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
The One ◽  
Integrated Performance ◽  
Quantity Of Heat ◽  
Side Flow ◽  
The Heat Transfer Coefficient

Flower baffle heat exchanger’s structure and design idea is introduced. Flower baffle heat exchanger has unique support structure. It can both enhance the efficiency of the heat transfer and reduce the pressure drop. Through the experimental study, under the same shell side flow, the heat transfer coefficient K which the distance between two flower baffles is 134mm is higher 3%~9% than the one of which the distances between two flower baffles are 163mm,123mm. The heat transfer coefficient K which the distance between two flower baffles is 147mm is close to the one of which the distances between two flower baffles is 134mm. The shell volume flow V is higher, the incremental quantity of heat transfer coefficient K is more. The integrated performance K/Δp of flower baffle heat exchanger which the distance between two flower baffles is 134mm is higher 3%~9% than the one of which the distances between two flower baffles are 163mm,123mm. Therefore, the best distance between two flower baffles exists between 134mm~147mm this experiment.

scholarly journals Studies on the Heat Transfer Coefficient and Pressure Drop of Several Kinds of Plate Heat Exchanger

1968 ◽  
Vol 32 (11) ◽  
pp. 1127-1132,a1 ◽  
Author(s):  
Katsuto Okada ◽  
Minobu Ono ◽  
Toshio Tomimum ◽  
Hirotaka Konno ◽  
Shigemori Ohtani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
The Heat Transfer Coefficient

Study on Free Convection Heat Transfer in a Finned Tube Array

2015 ◽  
Vol 23 (01) ◽  
pp. 1550007 ◽  
Author(s):  
Ryoji Katsuki ◽  
Tsutomu Shioyama ◽  
Chikako Iwaki ◽  
Tadamichi Yanazawa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Finned Tube ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Finned Tubes ◽  
Air Cooled Heat Exchanger ◽  
The Heat Transfer Coefficient

We have been developing a free convection air cooled heat exchanger without power supply to improve economic efficiency and mechanical reliability. However, this heat exchanger requires a larger installation area than the forced draft type air cooled heat exchanger since a large heating surface is needed to compensate for the small heat transfer by natural convection. Therefore, we have been investigating a heat exchanger consisting of an array of finned tubes and chimney to increase the heat transfer coefficient. Since the heat transfer characteristics of finned tube arrays have not been clarified, we conducted experiments with a finned tube array to determine the relation between the configuration of finned tubes and the heat transfer coefficient of a tube array. The results showed that the average heat transfer coefficient increased with pitch in the vertical direction, and became constant when the pitch was over five times the fin diameter. The average heat transfer coefficient was about 1.4 times higher than that of a single finned tube in free space. The ratio of the average heat transfer coefficient of the finned tube array with chimney to that of a single finned tube was found to be independent of the difference in temperature between the tube surface and air.

scholarly journals Experimental Research and Simulation of Fin and Tube Heat Exchanger

2017 ◽  
Vol 9 (4) ◽  
pp. 451-461
Author(s):  
Artur Rubcov ◽  
Sabina Paulauskaitė ◽  
Violeta Misevičiūtė
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Tests ◽  
Maximum Heat ◽  
Tube Heat Exchanger ◽  
The Heat Transfer Coefficient

The paper provides the results of experimental and theoretical test of a wavy fin and tube heat exchanger used to cool air in a ventilation system when the wavy fin of the heat exchanger is dry and wet. The experimental tests, performed in the range of 1000<Re<4500 of the Reynolds number applying LMTD-LMED methodology, determined the dependency of the heat transfer coefficient on the supplied air flow rate with the varying geometry of the heat exchanger (the number of tube rows, the distance between fins, the thickness of the fin and the diameter of the tube). The experimental tests were performed on 9 heat exchangers in heating and 6 heat exchangers in cooling mode. After processing the results of the experimental tests, empirical equation defining the characteristics of the heat transfer coefficient of all heat exchangers were derived. The maximum heat transfer coefficient deviation is 11.6 percent. The correction factor of the wet fin (Lewis number) depending on the number of Reynolds, which ranges from 0.75 to 1.1 also is determined. Maximum capacity deviation equals 3.7 percent. The obtained equations can only be applied to a certain group of heat exchangers (with the same shape of fins or the distance between the tubes). The results of the experimental test and simulation with ANSYS program are compared and the heat transfer coefficients vary from 6.5 to 11.4 percent.

scholarly journals Intensified Thermal Conductivity and Convective Heat Transfer of Ultrasonically Prepared CuO–Polyaniline Nanocomposite Based Nanofluids in Helical Coil Heat Exchanger

2019 ◽  
Vol 64 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Abhishek Lanjewar ◽  
Bharat Bhanvase ◽  
Divya Barai ◽  
Shivani Chawhan ◽  
Shirish Sonawane
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Base Fluid ◽  
Cuo Nanoparticles ◽  
The Heat Transfer Coefficient

In this study, investigation of convective heat transfer enhancement with the use of CuO–Polyaniline (CuO–PANI) nanocomposite basednanofluid inside vertical helically coiled tube heat exchanger was carried out experimentally. In these experiments, the effects of different parameters such as Reynolds number and volume % of CuO–PANI nanocomposite in nanofluid on the heat transfer coefficient of base fluid have been studied. In order to study the effect of CuO–PANI nanocomposite based nanofluid on heat transfer, CuO nanoparticles loaded in PANI were synthesized in the presence of ultrasound assisted environment at different loading concentration of CuO nanoparticles (1, 3 and 5 wt.%). Then the nanofluids were prepared at different concentrations of CuO–PANI nanocomposite using water as a base fluid. The 1 wt.% CuO–PANI nanocomposite was selected for the heat transfer study for nanofluid concentration in the range of 0.05 to 0.3 volume % and Reynolds number range of was 1080 to 2160 (±5). Around 37 % enhancement in the heat transfer coefficient was observed for 0.2 volume % of 1 wt.% CuO–PANI nanocomposite in the base fluid. In addition, significant enhancement in the heat transfer coefficient was observed with an increase in the Reynolds number and percentage loading of CuO nanoparticle in Polyaniline (PANI).

Sign in / Sign up

Export Citation Format

Share Document