scholarly journals Use of new similarities Bl and Blturb. to optimize the calculation and selection of heat exchange equipment for working with nanofluid coolants

2021 ◽  
Vol 23 (96) ◽  
pp. 46-53
Author(s):  
Y. Bilonoga ◽  
V. Stybel ◽  
O. Maksysko ◽  
U. Drachuk
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Seed Oil ◽  
Surface Forces ◽  
Express Method ◽  
Pumpkin Seed ◽  
Heat Exchange Equipment ◽  
Pumpkin Seed Oil ◽  
Selection Of

The problem of correct, exact calculation and selection of the optimal heat exchange equipment at use in it of nanoliquid heat carriers was investigated in the work. Classical numerical equations, which are widely used in the calculation and selection of heat exchangers with nanofluids, especially at temperatures above 50 °C, give an error of (15–20) % or more. This leads to the fact that the selected heat exchange equipment may not work efficiently with excessive consumption of thermal energy. A new approach to heat transfer processes is considered, taking into account the theory of J. Businesque, which gives an idea of turbulent viscosity and thermal conductivity, as well as comparing the resistance of the coolant flow to the nanoparticle with surface forces and considering turbulent fluid as Newtonian. It is shown that the consideration of the behavior of a nanoparticle in a turbulent liquid coolant without taking into account surface forces is inaccurate and erroneous. The physical content of the previously obtained new numbers of similarity Bl and Blturb is considered and the possibility of their effective application in the new numerical equation obtained by us for the calculation of heat exchangers using nanofluid coolants is shown. The existing express method of estimating the efficiency of nanorluids use in heat exchangers on the basis of classical numerical equations is analyzed and a new express method on the basis of a new numerical equation and new numbers of similarity Bl and Blturb is proposed. The proposed express calculation method shows that a mixture of H2O + EG (60:40) improves the heat transfer properties of water by + 12.86 %, and a mixture of (H2O + EG (60:40) + 1.5 % TiO2) and (milk) + 0.5 % pumpkin seed oil) – by +16.75 %, which corresponds to the experiments and our calculations, and the known express method based on classical numerical equations shows a deterioration of – 4.5 % and, accordingly, by – 1.2 %. An example of calculating the optimal shell-and-tube heat exchanger according to the new algorithm when heating milk with hot water with the addition of mixtures (H2O + EG (60:40) + 1.5 % TiO2) and accordingly (milk + 0.5 % pumpkin seed oil) fully confirms the correctness of the new express –method.

scholarly journals Application of porous materials in heat exchangers of heat supply system

2020 ◽  
Vol 22 (3) ◽  
pp. 3-13
Author(s):  
N. V. Rydalina ◽  
B. G. Aksenov ◽  
O. A. Stepanov ◽  
E. O. Antonova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Porous Materials ◽  
Heat Exchangers ◽  
Porous Metals ◽  
Porous Aluminum ◽  
Heat Exchange Equipment

Heat exchange capacity increase is one of the main concerns in the process of manufacturing modern heat exchange equipment. Constructing heat exchangers with porous metals is an advanced technique of heat exchange increase. A construction of heat exchangers with porous aluminum is described in this paper. The first heat transfer agent (hot water) flows through thin copper tubes installed within the porous aluminum. The second heat transfer agent (freon) flows through the pores of aluminum. Laboratory facility was created to study such a heat exchanger. Series of experiments were carried out. The purpose of the research presented here is to create a mathematical model of heat exchangers with porous metals, to perform analytical calculation of the heat exchangers and to confirm the results with the experimental data. In this case, one can`t use the standard methods of heat exchangers calculation because the pores inner surface area is indeterminate. The developed mathematical model is based on the equation describing the process of cooling the porous plate. A special mathematical technique is used to take into account the effect of tubes with water. The model is approximate but its solution is analytic. It is convenient. One can differentiate it or integrate it, which is very important. Comparison of calculated and experimental data is performed. Divergence of results is within the limits of experimental error. If freon volatilizes inside the heat exchanger, the heat of phase transition has to be taken into account alongside with heat capacity. The structure of the mathematical model makes it possible. The results presented in this paper prove the practicability of using porous materials in heat exchange equipment.

scholarly journals Matrix method to solve the inverse problem of heat transfer in heat exchangers

Vestnik IGEU ◽  
2021 ◽  
pp. 62-69
Author(s):  
V.P. Zhukov ◽  
A.Ye. Barochkin ◽  
M.S. Bobrova ◽  
A.N. Belyakov ◽  
S.I. Shuvalov
Keyword(s):  
Heat Transfer ◽  
Inverse Problem ◽  
Heat Exchange ◽  
Inverse Problems ◽  
Energy Saving ◽  
Heat Exchangers ◽  
Matrix Method ◽  
Heat Exchange Equipment ◽  
Design Calculations ◽  
Heat Carriers

Along with verification calculations of known designs of heat exchangers, in design engineering and when we develop new technologies, design calculations are necessary to solve the inverse problems of choosing the optimal designs and operating modes of equipment. Previously, the formulation and solution of inverse problems of classification and unsteady heat conduction have been considered, while the inverse problems of heat transfer in the design of heat exchange equipment are poorly presented in the literature. The development of methods to solve inverse problems in the design of heat exchange equipment is an urgent task of power industry. Matrix models of heat transfer based on mass and energy balance equations are used to formulate and solve inverse problems of heat exchange systems. Methods of mathematical programming are applied to solve inverse and optimization problems. For design calculations, a matrix method to solve inverse problems for choosing the design of devices and parameters of heat carriers that ensure the effective operation of the system is proposed. The inverse problem is formulated for the case of the sliding boundary of the beginning of the phase transition with the countercurrent type of movement of heat carriers. The obtained results can be used in power energy, chemical and food industries to improve the efficiency of designing resource-and energy-saving technologies. The solutions obtained can be implemented when developing measures to improve resource and energy saving technologies.

The antioxidant effects of pumpkin seed oil on subacute aflatoxin poisoning in mice

2011 ◽  
Vol 28 (12) ◽  
pp. 681-688 ◽  
Author(s):  
Gökhan Eraslan ◽  
Murat Kanbur ◽  
Öznur Aslan ◽  
Mürsel Karabacak
Keyword(s):  
Seed Oil ◽  
Pumpkin Seed ◽  
Pumpkin Seed Oil ◽  
Antioxidant Effects

scholarly journals POLYMERS AND PLASTIC USE FOR THE HEAT-EXCHANGE EQUIPMENT (REVIEW)

2020 ◽  
pp. 59-71
Author(s):  
I.O. Mikulionok
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Polymers And Plastics ◽  
Heat Exchange Equipment ◽  
Coefficient Of Heat Conductivity ◽  
Exchange Apparatus ◽  
Polymer Type

The possibility of use of the heat-exchangers in whole or in part manufactured with use of polymers and plastics is considered. Despite obvious, at first sight, inexpediency of use of polymeric materials in the heat-exchange equipment (low coefficient of heat conductivity, and also low, in comparison with metals, the strength properties of the majority of the most widespread polymers), «polymeric» heat-exchangers find application in various areas of the industry more and more surely. Classification of heat-exchange apparatuses which constructive elements are executed with use of polymeric materials is proposed. The following signs are the basis for classification: polymer type, a type of polymer meric material, type of the heat-exchange apparatus (a form of heat-exchange elements), reliance on polymeric materials in apparatuses, motion freedom of polymeric heat-exchange elements, level of assembly of a design, and also diameter of tubular elements. Critical analysis the most characteristic designs developed by domestic and foreign designers and inventors is carried out. Ref. 21, Fig. 13.

scholarly journals Determination of sesame oil, rice bran oil and pumpkin seed oil in ternary mixtures using FTIR spectroscopy and multivariate calibrations

Food Research ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Irnawati ◽  
S. Riyanto ◽  
S. Martono ◽  
Abdul Rohman
Keyword(s):  
Root Mean Square Error ◽  
Rice Bran ◽  
Seed Oil ◽  
Rice Bran Oil ◽  
Sesame Oil ◽  
Ftir Spectra ◽  
Ternary Mixtures ◽  
Mean Square ◽  
Pumpkin Seed ◽  
Pumpkin Seed Oil

Pumpkin seed oil (PSO), rice bran oil (RBO), sesame oil (SEO) are considered as functional oils due to its biological activities which are beneficial to human health, as a consequence, these oils had the higher price. This attracted unethical players to blend these oils with lower price oils, therefore, its authentication by analysis of purity levels of oils is very important. This study highlighted the potential application of FTIR spectroscopy and multivariate calibrations for analysis of PSO, RBO, and SEO in ternary mixtures. Individual FTIR spectra of studied oils as well as in ternary mixtures with certain compositions were scanned and pre-processed. Two multivariate calibrations of principle component regression (PCR) and partial least square regression (PLSR) were compared and used to build the prediction models at optimized FTIR spectra regions. The selection of multivariate calibrations, wavenumbers region, and FTIR spectra modes was based on the statistical parameters of highest R2 and lowest values of root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP). The results showed that PLSR using second derivative FTIR spectra at wavenumbers region of 3100-2750 and 1500-663 cm-1 was used to predict the levels of PSO in ternary mixtures with RBO and SEO with R2 > 0.99 in calibration and validation models along with RMSEC value of 0.0054% and RMSEP of 0.0179%. FTIR spectra using the second and first derivatives at wavenumbers of 3100-650 cm-1 were used for prediction of RBO and SEO in ternary mixture with PSO, respectively. It can be concluded that FTIR spectra combined with PLSR at certain wavenumbers region are accurate as indicated by high R2 values and precise as indicated by low values of RMSEC and RMSEP for analysis of PSO, RBO and SEO in ternary mixtures.

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