Semitheoretical Model of an Evaporator to Reduce Design Cycle Time

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
David Zietlow ◽  
Dan A. Spurgeon
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Transfer Rate ◽  
Air Conditioning ◽  
Development Cycle ◽  
Design Cycle ◽  
Product Development Cycle ◽  
Air Conditioning Systems ◽  
Original Equipment Manufacturers

Original equipment manufacturers are looking for ways to reduce the product development cycle. A tool to reduce this time in the design of air conditioning systems is introduced in this paper. This is done by using a semitheoretical model of each of the components of a system. The semitheoretical model has the advantage of reducing the number of geometrical inputs that need to be specified when compared with a “theoretical” model. This paper focuses on the most complex of the components—the evaporator. A tube and fin evaporator was successfully modeled and validated. The model was tuned using supplier component data (Luvata, 2005, Heatcraft Evaporator—Version 3.07.05.122 B-DHLEX.EVP) for the evaporator. The tuned accuracy of heat transfer rate and pressure drop, both air- and refrigerant-side, was within 5% over the range of conditions representative of air conditioning applications.

scholarly journals Improving the Heat Transfer Rate of Air Conditioning Condenser by Material Optimization

2021 ◽  
pp. 39-50
Author(s):  
A. A. Adegbola ◽  
O. A. Adeaga ◽  
A. O. Babalola ◽  
A. O. Oladejo ◽  
A. S. Alabi
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Heat Flux ◽  
Flow Rate ◽  
Transfer Rate ◽  
Air Conditioning ◽  
Static Pressure ◽  
Cfd Analysis ◽  
Condenser Tube ◽  
Total Heat Transfer

Air conditioning systems have condensers that remove unwanted heat from the refrigerant and transfer the heat outdoors. The optimization of the global exploit of heat exchanging devices is still a burdensome task due to different design parameters involved. There is need for more and substantial research into bettering cooling channel materials so as to ensure elevated performance, better efficiency, greater accuracy, long lasting and low cost heat exchanging. The aim of this research work is to improve the heat transfer rate of air conditioning condenser by optimizing materials for different tube diameters. Simulations using thermal analysis and Computational Fluid Dynamic (CFD) analysis were carried out to determine the better material and fluid respectively. The analysis was done using Analysis System software. Different parameters were calculated from the results obtained and graphs are plotted between various parameters such as heat flux, static pressure, velocity, mass flow rate and total heat transfer. The materials used for CFD analysis are R12 and R22, and for thermal analysis are copper and aluminium. From the CFD analysis, the result shows that R22 has more static pressure, velocity, mass flow rate and total heat transfer than R12 at condenser tube diameter 6 mm. In thermal investigation, the heat flux is more for copper material at condenser tube diameter 6 mm. Copper offers maximum heat flux. Also, refrigerant R22 scores maximum for the heat transfer criteria, but cannot be recommended due to toxicity

Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers

2013 ◽  
Vol 465-466 ◽  
pp. 500-504 ◽  
Author(s):  
Shahrin Hisham Amirnordin ◽  
Hissein Didane Djamal ◽  
Mohd Norani Mansor ◽  
Amir Khalid ◽  
Md Seri Suzairin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Three Dimensional ◽  
Considerable Effect ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Louvered Fin

This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capability of louvered fin in enhancing the performance of heat exchangers.

scholarly journals Design Evaluation for a Finned-Tube CO2 Gas Cooler in Residential Applications

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2428 ◽  
Author(s):  
Charalampos Alexopoulos ◽  
Osama Aljolani ◽  
Florian Heberle ◽  
Tryfon C. Roumpedakis ◽  
Dieter Brüggemann ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Air Conditioning ◽  
Design Procedure ◽  
Finned Tube ◽  
Co2 Gas ◽  
Ambient Temperatures ◽  
Overall Heat Transfer Coefficient

Towards the introduction of environmentally friendlier refrigerants, CO2 cycles have gained significant attention in cooling and air conditioning systems in recent years. In this context, a design procedure for an air finned-tube CO2 gas cooler is developed. The analysis aims to evaluate the gas cooler design incorporated into a CO2 air conditioning system for residential applications. Therefore, a simulation model of the gas cooler is developed and validated experimentally by comparing its overall heat transfer coefficient. Based on the model, the evaluation of different numbers of rows, lengths, and diameters of tubes, as well as different ambient temperatures, are conducted, identifying the most suitable design in terms of pressure losses and required heat exchange area for selected operational conditions. The comparison between the model and the experimental results showed a satisfactory convergence for fan frequencies from 50 to 80 Hz. The absolute average deviations of the overall heat transfer coefficient for fan frequencies from 60 to 80 Hz were approximately 10%. With respect to the gas cooler design, a compromise between the bundle area and the refrigerant pressure drop was necessary, resulting in a 2.11 m2 bundle area and 0.23 bar refrigerant pressure drop. In addition, the analysis of the gas cooler’s performance in different ambient temperatures showed that the defined heat exchanger operates properly, compared to other potential gas cooler designs.

Statistical Determination of the Experimental Channels Clogging Rates in Mini- and Microchannel Heat Exchangers

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Witold Rybiński ◽  
Jarosław Mikielewicz
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Cold Water ◽  
Nondestructive Method ◽  
Microchannel Heat Exchanger ◽  
Statistical Determination ◽  
Experimental Values

Abstract This paper presents a new statistical, nondestructive method for determination of the experimental channels clogging rate in a mini- or microchannel heat exchanger. Channels clogging may be caused by inaccurate fabrication of the heat exchanger or by fouling of microchannels during exploitation. The theoretical model, used in this method, predicts a significant increase of the pressure drop as the number of clogged microchannels increases. However, the exchanger’s heat transfer rate decreases moderately. It may partly be caused by the additional heat transfer in metal walls, bypassing the inactive, clogged microchannels. The presented method was tested on the prototype of a microchannel heat exchanger. The experimental values of the pressure drop of the hot and cold water flows are 2–5 times higher than the values predicted for clean microchannels. The experimental values for the pressure drop and heat transfer are in good agreement with the values calculated by the use of the theoretical model. The presented statistical method gives two channels clogging rates (for the “hot” and “cold” channels) obtained during normal exploitation without cutting (destroying) the heat exchanger.

Numerical Study of Fluid Flow and Heat Transfer Enhancement of Nanofluids over Tube Bank

2013 ◽  
Vol 388 ◽  
pp. 149-155 ◽  
Author(s):  
Mazlan Abdul Wahid ◽  
Ahmad Ali Gholami ◽  
H.A. Mohammed
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cross Flow ◽  
Bulk Temperature ◽  
Compact Heat Exchanger ◽  
Pure Fluid ◽  
Tube Banks

In the present work, laminar cross flow forced convective heat transfer of nanofluid over tube banks with various geometry under constant wall temperature condition is investigated numerically. We used nanofluid instead of pure fluid ,as external cross flow, because of its potential to increase heat transfer of system. The effect of the nanofluid on the compact heat exchanger performance was studied and compared to that of a conventional fluid.The two-dimensional steady state Navier-Stokes equations and the energy equation governing laminar incompressible flow are solved using a Finite volume method for the case of flow across an in-line bundle of tube banks as commercial compact heat exchanger. The nanofluid used was alumina-water 4% and the performance was compared with water. In this paper, the effect of parameters such as various tube shapes ( flat, circle, elliptic), and heat transfer comparison between nanofluid and pure fluid is studied. Temperature profile, heat transfer coefficient and pressure profile were obtained from the simulations and the performance was discussed in terms of heat transfer rate and performance index. Results indicated enhanced performance in the use of a nanofluid, and slight penalty in pressure drop. The increase in Reynolds number caused an increase in the heat transfer rate and a decrease in the overall bulk temperature of the cold fluid. The results show that, for a given heat duty, a mas flow rate required of the nanofluid is lower than that of water causing lower pressure drop. Consequently, smaller equipment and less pumping power are required.

Performance Evaluation of Tube-in-Tube Heat Exchanger Using Nanofluids

2015 ◽  
Vol 787 ◽  
pp. 72-76 ◽  
Author(s):  
V. Naveen Prabhu ◽  
M. Suresh
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Element Analysis ◽  
Tube Heat Exchanger

Nanofluids are fluids containing nanometer-sized particles of metals, oxides, carbides, nitrides, or nanotubes. They exhibit enhanced thermal performance when used in a heat exchanger as heat transfer fluids. Alumina (Al2O3) is the most commonly used nanoparticle due to its enhanced thermal conductivity. The work presented here, deals with numerical simulations performed in a tube-in-tube heat exchanger to study and compare flow characteristics and thermal performance of a tube-in-tube heat exchanger using water and Al2O3/water nanofluid. A local element-by-element analysis utilizing e-NTU method is employed for simulating the heat exchanger. Profiles of hot and cooling fluid temperatures, pressure drop, heat transfer rate along the length of the heat exchanger are studied. Results show that heat exchanger with nanofluid gives improved heat transfer rate when compared with water. However, the pressure drop is more, which puts a limit on the operating conditions.

The Development of Performance Prediction Methods for an Automotive CO2 A/C Cycle

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Akira Kaneko ◽  
Masafumi Katsuta ◽  
Takahiro Oshiro ◽  
Sangchul Bae ◽  
Shunji Komatsu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Performance Prediction ◽  
Air Conditioning ◽  
Cooling Capacity ◽  
Refrigeration Cycle ◽  
Air Conditioning System ◽  
Lubricant Oil ◽  
C Cycle ◽  
Simulation Results

In previous research, we have been focusing on the performance of the each element heat transfer and hydraulic performance of refrigeration cycle. Experimental investigations have been repeated several times, and finally, we have substantial database including the effect of lubricant oil. Moreover, the maldistribution of two-phase in an evaporator can be also predicted from the experimental database. Under these circumstances, this study is intended to effectively put the construction of an automotive CO2 air conditioning system into practical design use through the simulation using the above-mentioned database. This paper describes the refrigeration cycle performance prediction of each element (e.g., an evaporator, a gas-cooler, and so on) by a simulation using substantial database and various available correlations proposed by us and several other researchers. In the performance prediction model of heat exchangers, local heat transfer and flow characteristics are considered and, in addition, the effects of lubricant oil on heat transfer and pressure drop are duly considered. The comparison is also made between simulation results and bench test results using a real automotive air conditioning system. Finally, the developed simulation method can predict the cooling capacity successfully within ±10% for A/C system simulation. By incorporating the lubricant oil effect, the simulation results are improved to ±5% and ±15% for the cooling capacity and pressure drop for evaporator simulation, respectively.

scholarly journals Heat transfer properties of water and propylene-glycol as heat carries in air conditioning systems in mines

2019 ◽  
pp. 81-84
Author(s):  
L. Yu. Levin ◽  
◽  
Yu. A. Klyukin ◽  
M. D. Popov ◽  
S. V. Butakov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Propylene Glycol ◽  
Air Conditioning ◽  
Air Conditioning Systems ◽  
Transfer Properties

scholarly journals COMPUTER PROGRAM FOR CALCULATION MICROCHANNEL HEAT EXCHANGERS FOR AIR CONDITIONING SYSTEMS

2016 ◽  
Vol 52 (3) ◽  
Author(s):  
Olga V. Olshevska
Keyword(s):  
Heat Transfer ◽  
Computer Program ◽  
Heat Exchangers ◽  
Software Package ◽  
Air Conditioning ◽  
Correlation Equation ◽  
Design Time ◽  
Software Packages ◽  
Air Conditioning Systems ◽  
Thermodynamic Equations

Creating a computer program to calculate microchannel air condensers to reduce design time and carrying out variant calculations. Software packages for thermophysical properties of the working substance and the coolant, the correlation equation for calculating heat transfer, aerodynamics and hydrodynamics, the thermodynamic equations for the irreversible losses and their minimization in the heat exchanger were used in the process of creating. Borland Delphi 7 is used for creating software package.

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