scholarly journals Thermoeconomic analysis of spiral heat exchanger with constant wall temperature

2019 ◽  
Vol 23 (1) ◽  
pp. 401-410 ◽  
Author(s):  
Uros Milovancevic ◽  
Branislav Jacimovic ◽  
Srbislav Genic ◽  
Faraj El-Sagier ◽  
Milena Otovic ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Wall Temperature ◽  
Optimal Solution ◽  
Total Annual Cost ◽  
Geometrical Parameters ◽  
Outer Diameter ◽  
Plate Height ◽  
Constant Wall Temperature ◽  
Spiral Heat Exchanger ◽  
Wide Range

Thermoeconomic analysis of spiral heat exchanger is conducted. Different geometrical parameters, such as outer diameter, plate height, passage gap, etc. are used and varied in a wide range. Detailed thermal and total costs analyses were performed for two spiral heat exchanger with different process fluids (water and thermal oil) with temperature changes, while the wall temperature was kept constant (condensation). The results were shown graphically. It is determined that optimum values of number of entropy generation units correspond to minimum total annual cost. The optimal solution could be found in the recommended range of geometric sizes for defined inlet and outlet temperatures and process fluid-flow rate.

EFFECTS OF THERMAL CREEP ON COOLING OF MICROFLOWS IN SHORT MICROCHANNELS WITH CONSTANT WALL TEMPERATURE

2012 ◽  
Vol 23 (11) ◽  
pp. 1250072 ◽  
Author(s):  
ALI AMIRI-JAGHARGH ◽  
HAMID NIAZMAND ◽  
METIN RENKSIZBULUT
Keyword(s):  
Wall Temperature ◽  
Temperature Jump ◽  
Control Volume ◽  
Velocity Slip ◽  
Temperature Gradients ◽  
Thermal Creep ◽  
Inlet Temperature ◽  
Constant Wall Temperature ◽  
Aspect Ratios ◽  
Wide Range

Fluid flow and heat transfer in the entrance region of rectangular microchannels of various aspect ratios are numerically investigated in the slip-flow regime with particular attention to thermal creep effects. Uniform inlet velocity and temperature profiles are prescribed in microchannels with constant wall temperature. An adiabatic section is also employed at the inlet of the channel in order to prevent unrealistically large axial temperature gradients due to the prescribed uniform inlet temperature as well as upstream diffusion associated with low Reynolds number flows. A control-volume technique is used to solve the Navier–Stokes and energy equations which are accompanied with appropriate velocity slip and temperature jump boundary conditions at the walls. Despite the constant wall temperature, axial and peripheral temperature gradients form in the gas layer adjacent to the wall due to temperature jump. The simultaneous effects of velocity slip, temperature jump and thermal creep on the flow and thermal patterns along with the key flow parameters are examined in detail for a wide range of cross-sectional aspect ratios, and Knudsen and Reynolds numbers. Present results indicate that thermal creep effects influence the flow field and the temperature distribution significantly in the early section of the channel.

ENTRANCE EFFECTS OF THERMAL CREEP ON FLUID HEATING IN RECTANGULAR MICROCHANNELS

2013 ◽  
Vol 24 (08) ◽  
pp. 1350054 ◽  
Author(s):  
ALI AMIRI-JAGHARGH ◽  
HAMID NIAZMAND ◽  
METIN RENKSIZBULUT
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Temperature Jump ◽  
Velocity Slip ◽  
Temperature Gradients ◽  
Thermal Creep ◽  
Constant Wall Temperature ◽  
Rectangular Microchannels ◽  
Aspect Ratios ◽  
Wide Range

The effects of thermal creep on the development of gaseous fluid flow and heat transfer in rectangular microchannels with constant wall temperature are investigated in the slip-flow regime. Thermal creep arises from tangential temperature gradients, which may be significant in the entrance region of channels, and affects the velocity and temperature fields particularly in low Reynolds number flows. In the present work, the Navier–Stokes and energy equations coupled with velocity-slip and temperature-jump conditions applied at the channel walls are solved numerically using a control-volume technique. Despite the constant wall temperature, tangential temperature gradients form in the gas layer adjacent to the wall due to the temperature-jump condition. The effects of slip/jump and thermal creep on the flow patterns and parameters are studied in detail for a wide range of channel aspect ratios and, Knudsen and Reynolds numbers. Furthermore, the effects of variable properties on velocity-slip and, friction and heat transfer coefficients are also examined.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

Plate-fin heat exchanger network modeling, design and optimization – a novel and comprehensive algorithm

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Reza Ramezanpour Jirandeh ◽  
Mehrangiz Ghazi ◽  
Amir Farhang Sotoodeh ◽  
Mohammad Nikian
Keyword(s):  
Heat Exchanger ◽  
Objective Function ◽  
Heat Exchangers ◽  
Annual Cost ◽  
Cross Flow ◽  
Total Annual Cost ◽  
Geometrical Parameters ◽  
Heat Exchanger Network ◽  
Content Type ◽  
Decision Variables

Purpose The purpose of this paper is to present a novel and applied method for optimum designing of plate-finned heat exchanger network. Considering the total annual cost as the objective function, a network of plate-finned heat exchanger is designed and optimized. Design/methodology/approach Accurate evaluation of plate-finned heat exchanger networks depends on different fin types with 10 different geometrical parameters of heat exchangers. In this study, fin numbers are considered as the main decision variables and geometrical parameters of fins are considered as the secondary decision variables. The algorithm applies heat transfer and pressure drop coefficients correction method and differential evolution (DE) algorithm to obtain the optimum results. In this paper, optimization and minimization of the total annual cost of heat exchanger network is considered as the objective function. Findings In this study, a novel and applied method for optimum designing of plate-finned heat exchanger network is presented. The comprehensive algorithm is applied into a case study and the results are obtained for both counter-flow and cross-flow plate-finned heat exchangers. The total annual cost and total area of the network with counter-flow heat exchangers were 12.5% and 23.27%, respectively, smaller than the corresponding values of the network with cross-flow heat exchanger. Originality/value In this paper, a reliable method is used to design, optimize parameters and the economic optimization of heat exchanger network. Taking into account the importance of plate-finned heat exchangers in industrial applications and the complexity in their geometry, the DE methodology is adopted to obtain an optimal geometric configuration. The total annual cost is chosen as the objective function. Applying this technique to a case study illustrates its capability to accurate design plate-finned heat exchangers to improve the objective function of the heat exchanger network from the economic viewpoint with the design of details.

Genetic Algorithm Based Design and Optimization of an Outer-Fins and Inner-Fins Tube Heat Exchanger

2007 ◽  
Author(s):  
G. N. Xie ◽  
M. Zeng ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Annual Cost ◽  
Total Annual Cost ◽  
Geometrical Parameters ◽  
Tube Heat Exchanger ◽  
Design And Optimization ◽  
Extended Surfaces

One of passive enhancement techniques, Extended Surfaces, are commonly employed in many heat exchangers to enlarge the heat transfer area on gases side because of the low heat transfer coefficients, which may be 10 to 100 times smaller than those of liquids side. The use of extended surfaces (or referred to as finned surfaces) will reduce the thermal resistance of gases side. Enhanced heat transfer coefficient will be achieved by using the basic surface geometries: plate-fin and tube-fin. With respect to the tube-fin type heat exchanger, fins may be employed outside tubes (herein called outer-fins) to enhance the heat transfer of shell-side, and alternatively fins may be also employed inside tubes (herein called inner-fins) to increase the intensity of heat transfer of tube-side. The desire to accomplish the gas-to-gas heat exchange through the tubular heat exchangers will lead to develop heat transfer enhancement techniques for outside and inside tubes. Therefore based on integration with such two mechanisms, namely, outer-fins and inner-fins of enhancement heat transfer techniques, a kind of outer-fins and inner-fins tube heat exchanger has been preliminary proposed (ASME-IGTI, Paper No.2006-90260 [20]). Such heat exchanger is potentially used in gas-to-gas heat exchangers, especially used for highpressure operating conditions, where the plate-fin heat exchangers might not be applicable. In general, the design task is a complex trial-and-error process and there is always the possibility that the design results such as geometrical parameters are not the optimum. Therefore, the motivation of this paper is to conduct optimum designs of such heat exchanger (hereafter called Outer-Fins and Inner-Fins tube Heat Exchanger, OFIF HE). A computational intelligent technique, Genetic Algorithm (GA) is applied to search and optimize geometrical parameters of the OFIF HE. The minimum total volume or minimum total annual cost of such OFIF HE is taken as an objective function in the GA respectively. The results show that the optimized OFIF HE provides lower total volume or lower total annual cost than those presented in previous work. The method is universal and may be used for design and optimization of OFIF HEs under different specified duties and design objectives.

scholarly journals Model-Based Cost Optimization of Double-Effect Water-Lithium Bromide Absorption Refrigeration Systems

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 50 ◽  
Author(s):  
Sergio Mussati ◽  
Seyed Mansouri ◽  
Krist Gernaey ◽  
Tatiana Morosuk ◽  
Miguel Mussati
Keyword(s):  
Heat Exchanger ◽  
Optimal Solution ◽  
Double Effect ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Process Unit ◽  
Absorption Refrigeration ◽  
Optimal Process ◽  
Total Cost ◽  
Wide Range

This work presents optimization results obtained for a double-effect H2O-LiBr absorption refrigeration system considering the total cost as minimization criterion, for a wide range of cooling capacity values. As a model result, the sizes of the process units and the corresponding operating conditions are obtained simultaneously. In this paper, the effectiveness factor of each proposed heat exchanger is considered as a model optimization variable which allows (if beneficial, according to the objective function to be minimized) its deletion from the optimal solution, therefore, helping us to determine the optimal configuration. Several optimization cases considering different target levels of cooling capacity are solved. Among the major results, it was observed that the total cost is considerably reduced when the solution heat exchanger operating at low temperature is deleted compared to the configuration that includes it. Also, it was found that the effect of removing this heat exchanger is comparatively more significant with increasing cooling capacity levels. A reduction of 9.8% in the total cost was obtained for a cooling capacity of 16 kW (11,537.2 $·year−1 vs. 12,794.5 $·year−1), while a reduction of 12% was obtained for a cooling capacity of 100 kW (31,338.1 $·year−1 vs. 35,613.9 $·year−1). The optimization mathematical model presented in this work assists in selecting the optimal process configuration, as well as determining the optimal process unit sizes and operating conditions of refrigeration systems.

Analytical Solution of Temperature Field in Micro-Poiseuille Flow With Constant Wall Temperature

2008 ◽  
Author(s):  
Masoud Darbandi ◽  
Salman SafariMohsenabad ◽  
Shidvash Vakilipour
Keyword(s):  
Temperature Field ◽  
Wall Temperature ◽  
Analytical Solutions ◽  
Analytical Study ◽  
Numerical Solutions ◽  
Experimental Studies ◽  
Constant Wall Temperature ◽  
Power Series Method ◽  
The Past ◽  
Wide Range

The analytical study of microchannels has been considered as a preliminary approach to alleviate the difficulties which are normally encountered in numerical and experimental studies. Among the analytical solutions, those with high robustness and low complexities are certainly more attractive. In this work, we present a theoretical approach to predict the temperature field in micro-Poiseuille channel flow with constant wall temperature. The use of power series method simplifies the solution in the current analytical approach. The current analytical derivations are examined for channels with both hot-wall and cold-wall conditions. The current solutions agree well with the numerical solutions for a wide range of Knudsen numbers. Contrary to the past analytical solutions and in spite of using a simple and robust approach, the current formulations predict the temperature field in the channel readily.

Total Temperature Measurement of Gas Flow in Micro-Tube With Constant Wall Temperature

2014 ◽  
Author(s):  
Seiryu Matsushita ◽  
Taiki Nakamura ◽  
Chungpyo Hong ◽  
Yutaka Asako
Keyword(s):  
Kinetic Energy ◽  
Temperature Measurement ◽  
Wall Temperature ◽  
Gas Flow ◽  
Atmospheric Condition ◽  
Gas Velocity ◽  
Constant Wall Temperature ◽  
Choked Flow ◽  
Wide Range ◽  
Total Temperature

This paper describes experimental results on total temperature measurement of nitrogen micro-jet from micro-tubes outlet measured for the wide range from unchoked to choked flow. The experiments were preformed for a stainless micro-tube of 523.2 μm in diameter whose temperature difference between the wall and inlet was maintained at 2, 5 and 10 K by circulating water around the micro-tube, respectively. The gas flows out to the atmospheric condition. A thermally insulated tube of foamed polystyrene with six baffles fabricated by the companion paper (IMECE-36965) where the gas velocity reduces and the kinetic energy is converted into the thermal energy, was attached to the outlet of the micro-tube. The inner diameter of the polystyrene tube is 22 mm. The baffles are equally spaced and the intervals of the baffles tested are 5 and 10 mm to investigate the effect of the interval of the baffle on the reduction of the gas velocity. The gas temperature measured by thermocouples at locations of baffles is considered as total temperature. The measured total temperature is higher than the wall temperature and increases with increasing the stagnation pressure (Reynolds number) for unchoked flow since the additional heat transfer from the wall to the gas near the micro-tube outlet caused by the temperature fall due to the energy conversion into the kinetic energy. It decreases in the insulated tube for chocked flow since Joule-Thomson effect is dominant in the insulated tube. The measured total temperatures are compared with results obtained by numerical computations.

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