Effectiveness of 6-Row Crossflow Heat Exchangers Alternating Circuitry

Volume 3 ◽  
2004 ◽  
Author(s):  
Tony D. Chen
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Fluid Temperature ◽  
Basic Tool ◽  
Capacity Ratio ◽  
Comparison Of Effectiveness ◽  
Air Conditioning Systems ◽  
Flow Maldistribution

Air-cooled heat exchangers with six tube rows are commonly seen in air-conditioning systems for large commercial and industry buildings. The analytical solutions of heat exchanger effectiveness for 6-row plate fin-and-tube heat exchangers with alternating circuitries have been derived and expressed explicitly in terms of heat capacity ratio, number of transfer units, and the dimensionless fluid temperature to the inlet of each row and section in this study. This set of exact solutions serve as a basic tool in designing heat exchanger circuitry to its most accurate effectiveness. Comparison of effectiveness between pure and alternating circuiting for 6-row crossflow heat exchangers shows that alternating circuiting could have less effectiveness than pure crossflow with identical circuiting from 1.0 to 7.9% for cases of NTUs range from 1.0 to 3.0 and capacity ratio of 0.5. Nevertheless, alternating circuit has its benefit of lowering the temperature difference between air- and refrigerant-flow, which leads to less pressure drop and less flow maldistribution, therefore resulting in better overall heat exchanger performance.

Effectiveness of 3-Row Crossflow Heat Exchangers With Alternating Circuitry

2003 ◽  
Author(s):  
Tony D. Chen
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
The Other ◽  
Basic Tool ◽  
Tube Heat Exchanger ◽  
Fin Tube ◽  
Comparison Of Effectiveness ◽  
Air Conditioning Systems

Air-cooled heat exchangers with three tube rows are commonly seen in domestic air-conditioning systems. The analytical solutions of heat exchanger effectiveness for three-row plate fin-and-tube heat exchangers with alternating circuitries have been derived and expressed explicitly in terms of heat capacity ratio and number of transfer units in the recent study. These set of exact solutions serve as a basic tool in designing heat exchanger circuitry to its most accurate possible effectiveness. Comparison of plate-fin-tube heat exchanger effectiveness between airside unmixed and mixed for three-row configurations shows that the effectiveness could be different from 0.3 to 2.4% for the NTUs (Number of Thermal Units) range from 1.0 to 3.0. On the other hand, the result of the comparison of effectiveness between identical and alternating circuiting for 3-row crossflow heat exchangers shows that alternating circuiting could have less effectiveness than identical circuiting from 0.4 to 8.8% in the NTUs range from 1.0 to 3.0. Nevertheless, alternating circuit has its benefit for lower NTU cases, result shows that it could have 1.7 to 0.1% advantages over identical flow arrangement for 2-row heat exchangers with NTUs range from 1.0 to 2.0.

A New Type of Heat Exchanger for Ventilation in Buildings with Nearly-Zero Energy Consumption

2014 ◽  
Vol 899 ◽  
pp. 231-234 ◽  
Author(s):  
Petr Horák ◽  
Adam Pavel ◽  
Iva Ambrožová
Keyword(s):  
Energy Consumption ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Lower Cost ◽  
Great Promise ◽  
Zero Energy ◽  
Heating Performance ◽  
New Type ◽  
Air Conditioning Systems

This article describes a new type of hollow-fiber heat exchanger that provides similar heating performance to conventional metal heat exchangers commonly used in air conditioning systems but at lower cost and greater simplicity. While factors such as fragility and element fouling have yet to be optimized, the exchanger shows great promise for application in buildings aiming at close-to-zero energy consumption.

THE ANALYSIS OF EXERGY EFFICIENCY IN THE LOW TEMPERATURE HEAT EXCHANGER

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3497-3499 ◽  
Author(s):  
LAN PENG ◽  
YOU-RONG LI ◽  
SHUANG-YING WU ◽  
BO LAN
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Heat Exchanger ◽  
Low Temperature ◽  
Transfer Process ◽  
Heat Exchangers ◽  
Heat Transfer Process ◽  
Exergy Efficiency ◽  
Capacity Ratio ◽  
Temperature Heat

Based on the analyzing of the thermodynamic performance of the heat transfer process in the low temperature heat exchangers, the exergy efficiency of the heat transfer process is defined and a general expression for the exergy efficiency is derived, which can be used to discuss the effect of heat transfer units number and heat capacity ratio of fluids on the exergy efficiency of the low temperature heat exchanger. The variation of the exergy efficiency for several kinds of flow patterns in the low heat exchangers is compared and the calculating method of the optimal values of heat capacity ratio for the maximum exergy efficiency is given.

The empirical study of a four-row heat pipe heat exchanger to predict the year-round energy recovery in the tropics

2011 ◽  
Vol 32 (4) ◽  
pp. 307-327 ◽  
Author(s):  
YH Yau ◽  
M Ahmadzadehtalatapeh
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Heat Exchangers ◽  
Air Conditioning ◽  
Energy Recovery ◽  
Empirical Performance ◽  
Air Conditioning Systems ◽  
The Tropics ◽  
The Impact ◽  
Pipe Heat

The effect of heat pipe heat exchanger on the heat recovery was studied in the tropics. The performance of the heat exchanger was monitored during the one week of operation (168 h) to find out the performance characteristic curves. Three coil face velocities namely, 2, 2.2 and 2.5 m/s were tested and the temperature of return air was controlled at 24°C. The relevant empirical equations were then employed for the hour-by-hour prediction of the energy recovery by the heat pipe heat exchanger for the whole year. The impact of inside design temperature on the heat recovery by the heat exchanger was also studied. The thermal performance of the heat pipe heat exchanger was simulated based on the effectiveness-NTU method and the theoretical values were compared with the experimental data. Practical application: Performance improvement of the heating, ventilating and air conditioning systems is a challenge to the designers. The results obtained from this research work could serve as a practical guide for engineers who are intending to use heat pipe heat exchangers in the heating, ventilation and air conditioning systems operating in tropical climates. Engineers and researchers have the potential to use the recommended empirical performance equations to examine the impact of heat pipe heat exchangers on the performance of the current air conditioning systems. Moreover, these empirical performance equations enable the year-round operating effect of heat pipe heat exchangers on energy savings to be predicted realistically.

scholarly journals Study of the Performance of a Novel Radiator with Three Inlets and One Outlet Based on Topology Optimization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 594
Author(s):  
Tao Zhou ◽  
Bingchao Chen ◽  
Huanling Liu
Keyword(s):  
Topology Optimization ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Exchange Capacity ◽  
Numerical Results ◽  
Fluid Temperature ◽  
Channel Depth ◽  
Goal Model ◽  
Flow And Heat Transfer

In recent years, in order to obtain a radiator with strong heat exchange capacity, researchers have proposed a lot of heat exchangers to improve heat exchange capacity significantly. However, the cooling abilities of heat exchangers designed by traditional design methods is limited even if the geometric parameters are optimized at the same time. However, using topology optimization to design heat exchangers can overcome this design limitation. Furthermore, researchers have used topology optimization theory to designed one-to-one and many-to-many inlet and outlet heat exchangers because it can effectively increase the heat dissipation rate. In particular, it can further decrease the hot-spot temperature for many-to-many inlet and outlet heat exchangers. Therefore, this article proposes novel heat exchangers with three inlets and one outlet designed by topology optimization to decrease the fluid temperature at the outlet. Subsequently, the effect of the channel depth on the heat exchanger design is also studied. The results show that the type of exchanger varies with the channel depth, and there exists a critical depth value for obtaining the minimum substrate temperature difference. Then, the flow and heat transfer performance of the heat exchangers are numerically investigated. The numerical results show that the heat exchanger derived by topology optimization with the minimum temperature difference as the goal (Model-2) is the best design for flow and heat transfer performance compared to other heat sink designs, including the heat exchanger derived by topology optimization having the average temperature as the goal (Model-1) and conventional straight channels (Model-3). The temperature difference of Model-1 can be reduced by 37.5%, and that of Model-2 can be decreased by 62.5% compared to Model-3. Compared with Model-3, the thermal resistance of Model-1 can be reduced by 21.86%, while that of Model-2 can be decreased by 47.99%. At room temperature, we carried out the forced convention experimental test for Model-2 to measure its physical parameters (temperature, pressure drop) to verify the numerical results. The error of the average wall temperature between experimental results and simulation results is within 2.6 K, while that of the fluid temperature between the experimental and simulation results is within 1.4 K, and the maximum deviation of the measured Nu and simulated Nu was less than 5%. This indicated that the numerical results agreed well with the experimental results.

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

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