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.

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.

Experimental Research on Microchannel Heat Exchanger Performance for Residential Air Conditioner Applications

2009 ◽  
Author(s):  
Jianghong Wu ◽  
Shuangfeng Wang ◽  
Yunting Ge
Keyword(s):  
Heat Exchanger ◽  
Thermal Performance ◽  
Air Conditioning ◽  
The Other ◽  
Air Conditioner ◽  
Round Tube ◽  
Tube Heat Exchanger ◽  
Face Area ◽  
Residential Air Conditioning ◽  
Air Conditioning Systems

Two type condensers of R22 residential air conditioning systems were investigated in this study. Two R22 residential air-conditioning systems, one with a microchannel condenser and the other with a round-tube condenser, were examined experimentally, while the other components of the two systems were identical except the condensers. Based on the principle of the microchannel condensation, the analysis of heat transfer along parallel heat exchanger was conducted. The non-uniform air velocity distribution at the face of the microchannel condenser and refrigerant distribution in headers were taken into account in this research. The mechanism and possibility of the superior thermal performance as compared with conventional fin-tube heat exchangers were discussed. In addition, the maximum of thermal performance influenced by the running parameter was experimentally measured. The experimental results show that with one third face area of round tube heat exchanger, microchannel condenser’s pressure drop increase around 12–23% and refrigeration output increase 2–5%, refrigerant charge decreases around 50%, it is found to be a promising candidate for residential air conditioning condenser.

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.

Finned Elliptical Tubes and Their Application in Air-Cooled Heat Exchangers

1966 ◽  
Vol 88 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Franz J. Schulenberg
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Heat Transfer Surface ◽  
Great Success ◽  
Sufficient Criterion ◽  
Tube Heat Exchanger ◽  
Circular Tubes ◽  
Fin Tube

Finned circular tubes have been used exclusively in air-cooled heat exchangers built for the American petroleum and chemical industries. In Europe, however, other tube geometries, in particular, finned elliptical tubes, have been used with great success. In this paper, the theory of the finned elliptical tube and its application in air-cooled heat exchangers are discussed. Finned circular and elliptical tubes are compared; it is shown that the developed heat transfer surface alone is not a sufficient criterion for predicting the performance of an air-cooled fin-tube heat exchanger.

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.

scholarly journals Flow across a Fin-tube Heat Exchanger for Air-conditioning Equipment

1996 ◽  
Vol 16 (1Supplement) ◽  
pp. 175-178
Author(s):  
Syuichi KIKUKAWA ◽  
Hajime YAMAGUCHI ◽  
Moriyosi SAKAMOTO
Keyword(s):  
Heat Exchanger ◽  
Air Conditioning ◽  
Tube Heat Exchanger ◽  
Fin Tube ◽  
Conditioning Equipment

A Uniquely Finned Tube Heat Exchanger Design of a Condenser for Heavy-Duty Air Conditioning Systems

2020 ◽  
Vol 28 (01) ◽  
pp. 2050004 ◽  
Author(s):  
Ahmad M. Abubaker ◽  
Yousef S. H. Najjar ◽  
Adnan Darwish Ahmad
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Air Conditioning ◽  
Water Pressure ◽  
Unit Length ◽  
Finned Tube ◽  
Coefficient Of Performance ◽  
Tube Heat Exchanger ◽  
Finned Tube Heat Exchanger ◽  
Air Conditioning Systems

This study introduces the design of a novel condenser for air conditioning systems. Enhancement of performance of the system was manifested by increasing the coefficient of performance (COP), decreasing the pressure drop and the power consumed by the refrigerant compressor and the cooling water pump. The design consists of an adiabatic double-pipe heat exchanger with longitudinal rectangular fins. This model can enhance heat transfer coefficient and expose more area per unit length. This novel design supersedes other conventional condenser designs by 4.7% higher COP, 8.2% lower water pressure drop, 4.68% lower compressor power. Two refrigerants have been examined in the study; R-134a which is used in commercial and industrial chillers and R-1234ze which has low global warming potential.

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.

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