Design and Optimization of Air-Cooled Heat Exchangers

1982 ◽  
Vol 104 (4) ◽  
pp. 683-690 ◽  
Author(s):  
C. P. Hedderich ◽  
M. D. Kelleher ◽  
G. N. Vanderplaats
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Numerical Optimization ◽  
Tube Heat Exchanger ◽  
Design And Optimization ◽  
Heat Exchanger Design ◽  
Finned Tube Heat Exchanger ◽  
Augmented Lagrange Multiplier

A computer code has been developed for analysis of air-cooled heat exchangers and was coupled with a numerical optimization program to produce an automated air-cooled, heat-exchanger design and optimization procedure. A general iteration free approximation method was used for the analysis which calculates the mean overall heat-transfer coefficient and the overall pressure drop for many flow arrangements. The analysis takes into account the variation of the heat-transfer coefficients and the pressure drop with temperature and/or length of flow path. The code is not limited to surfaces found in the literature, but will accommodate any triangular pitch bank of finned tubes in multiple-pass configurations. The numerical optimization code is a general purpose program based on the Method of Feasible Directions and the Augmented Lagrange Multiplier Method. The capability is demonstrated by the design of an air-to-water finned-tube heat exchanger and is shown to be a useful tool for heat exchanger design.

Impact of an Anisotropic Fin Surface Design on the Thermal-Hydraulic Performance of a Plain-Fin-and-Tube Heat Exchanger

2011 ◽  
Author(s):  
Rong Yu ◽  
Andrew D. Sommers ◽  
Nicole C. Okamoto ◽  
Koushik Upadhyayula
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Hydraulic Performance ◽  
Normal Operation ◽  
Surface Design ◽  
Tube Heat Exchanger ◽  
Silane Coating ◽  
Side Pressure

In this study, we have explored the effectiveness of heat exchangers constructed using anisotropic, micro-patterned aluminum fins to more completely drain the condensate that forms on the heat transfer surface during normal operation with the aim of improving the thermal-hydraulic performance of the heat exchanger. This study presents and critically evaluates the efficacy of full-scale heat exchangers constructed from these micro-grooved surfaces by measuring dry/wet air-side pressure drop and dry/wet air-side heat transfer data. The new fin surface design was shown to decrease the core pressure drop of the heat exchanger during wet operation from 9.3% to 52.7%. Furthermore, these prototype fin surfaces were shown to have a negligible effect on the heat transfer coefficient under both dry and wet conditions while at the same time reducing the wet airside pressure drop thereby decreasing fan power consumption. That is to say, this novel fin surface design has shown the ability, through improved condensate management, to enhance the thermal-hydraulic performance of plain-fin-and-tube heat exchangers used in air-conditioning applications. This paper also presents data pertaining to the durability of the alkyl silane coating.

Comparative Experimental Study on Performance of Corrugated Tube and Straight Tube Heat Exchanger

2012 ◽  
Vol 560-561 ◽  
pp. 156-160
Author(s):  
Lin Ping Lu ◽  
Liang Ying
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Straight Tube ◽  
Lower Stress ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Corrugated Tube

The experiments on heat transfer coefficient, pressure drop and thermal stress were done to heat exchangers with corrugated tubes and staight tubes. By analyising and comparing the heat transfer coeffient, pressure drop in tube side and shell side and axial force and stress, some conclusions can be conducted that the corrugated tube heat exchanger has better heat transfer coeffient, higher pressure drop and much lower stress caused by temperatur difference, also, it has obvious advantages under the circumstance of low Reynolds number and high temperature difference.

Numerical Simulation of the Flow Boiling Heat Transfer Performance of R134a in a Microchannel Evaporator With Louvered Fins

2011 ◽  
Author(s):  
Justin J. Gossard ◽  
Andrew D. Sommers
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Flow Boiling ◽  
Control Volume ◽  
Cooling Capacity ◽  
Heat Exchanger Design ◽  
Microchannel Tubes ◽  
Louvered Fins

The need for more compact and more efficient heat exchangers in the aerospace, automotive, and HVAC&R industries has led to the development of heat exchangers that utilize minichannel or microchannel tubes coupled with louvered fins. Minichannel and microchannel heat exchangers exhibit enhanced heat transfer with a minimal increase in pressure drop over conventional round tube, plain fin heat exchangers often with a significant reduction in the required refrigeration charge and overall heat exchanger size. This paper presents the development and validation of a finite volume, steady-state evaporator model to be used as an aid in heat exchanger design and analysis. The model focuses on evaporator geometries that include minichannel and microchannel tubes with louvered fins and headers. Multiple published correlations provide the user with options for calculating the air-side and refrigerant-side heat transfer and pressure drops within the control volume. Once the model was validated, it was then briefly used to study the effects of maldistribution of refrigerant within the inlet headers on the cooling capacity and refrigerant side pressure drop.

Development of a Microchannel Heat Exchanger for Aerospace Applications

2012 ◽  
Author(s):  
Hal Strumpf ◽  
Zia Mirza
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
State Of The Art ◽  
Design And Optimization ◽  
Microchannel Heat Exchanger ◽  
Aerospace Applications ◽  
Accurate Design ◽  
Adjustment Factors

Honeywell Aerospace has been developing microchannel heat exchangers for aerospace use. These heat exchangers offer significant reduction in volume and some reduction in weight compared to state-of-the-art aerospace heat exchangers constructed using offset plate and fin interupted surfaces. A microchannel heat exchanger was designed based on the requirements and available envelope for an aerospce liquid-to-air heat exchanger presently in service. The new micochannel heat exchanger was fabricated and a full testing campaign was undertaken to validate the design approach and generate appropriate adjustment factors for pressure drop and heat transfer. Based on this correlated model, the heat exchanger was re-sized for the required conditions. This updated design shows a significant reduction in size compared to the existing heat exchanger. In addition, Honeywell now has a validated approach enabling accurate design and optimization of microchannel heat exchangers for diverse problem conditions.

Thermal Design of Heat Exchanger With Fins Inside and Outside Tubes

2006 ◽  
Author(s):  
G. N. Xie ◽  
Q. Y. Chen ◽  
M. Zeng ◽  
Q. W. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Total Pressure ◽  
Thermal Design ◽  
Operating Pressure ◽  
Heat Transfer Area ◽  
Tube Heat Exchanger ◽  
Total Pressure Drop

Compact heat exchangers such as tube-fin types and plate-fin types are widely used for gas-liquid or gas-gas applications. Some examples are air-coolers, fan coils, regenerators and recuperators in micro-turbines. In this study, thermal design of fin-and-tube (tube-fin) heat exchanger performance with fins being employed outside and inside tubes was presented, with which designed plate-fin heat exchanger was compared. These designs were performed under identical mass flow rate, inlet temperature and operating pressure on each side for recuperator in 100kW microturbine as well as specified allowable fractions of total pressure drop by means of Log-Mean Temperature Difference (LMTD) method. Heat transfer areas, volumes and weights of designed heat exchangers were evaluated. It is shown that, under identical heat duty, fin-and-tube heat exchanger requires 1.8 times larger heat transfer area outside tubes and volume, 0.6 times smaller heat transfer area inside tubes than plate-fin heat exchanger. Under identical total pressure drop, fin-and-tube heat exchanger requires about 5 times larger volume and heat transfer area in gas-side, 1.6 times larger heat transfer area in air-side than plate-fin heat exchanger. Total weight of fin-and-tube heat exchanger is about 2.7 times higher than plate-fin heat exchanger, however, the heat transfer rate of fin-and-tube heat exchanger is about 1.4 times larger than that of plate-fin heat exchanger. It is indicated that, both-sides finned tube heat exchanger may be used in engineering application where the total pressure drop is severe to a small fraction and the operating pressure is high, and may be adopted for recuperator in microturbine.

Air Cooled Compact Heat Exchanger Design for Avionics Thermal Management Using Published Test Data

2003 ◽  
Author(s):  
George Hall ◽  
James Marthinuss
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Thermal Management ◽  
Test Data ◽  
Heat Exchangers ◽  
Optimized Design ◽  
Compact Heat Exchanger ◽  
Compact Heat Exchangers ◽  
Heat Exchanger Design

This paper will discuss air-cooled compact heat exchanger design using published data. Kays & London’s “Compact Heat Exchangers” [1] contains measured heat transfer and pressure drop data on a variety of circular and rectangular passages including circular tubes, tube banks, straight fins, louvered fins, strip or lanced offset fins, wavy fins and pin fins. While “Compact Heat Exchangers” is the benchmark for air cooled heat exchanger test data it makes no attempt to summarize the results or steer the thermal designer to an optimized design based on the different factors or combination of heat transfer, pressure drop, size, weight, or even cost. Using this reduced data and the analytical solutions provided highly efficient compact heat exchangers could be designed. This paper will guide a thermal engineer toward this optimized design without having to run trade studies on every possible heat exchanger design configuration. Typical applications of published fin data in the aerospace and military electronics include electronics cold plates, card rack walls and air-to-air heat exchangers using fan driven and ECS driven air. Airborne electronics often require extremely dense packaging techniques to fit all the required functions into the available volume. While leaving little room for cooling hardware this also drives power densities up to levels (20 W/sq-cm) that require highly efficient heat transfer techniques. Several design issues are discussed including pressure drop, heat transfer, compactness, axial conduction, flow distribution and passage irregularities (bosses). Comparisons between fin performance are made and conclusions are drawn about the applicability of each type of fin to avionics thermal management.

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.

Application of Nanofluids in a Shell-and-Tube Heat Exchanger

2013 ◽  
Author(s):  
Jonathan Cox ◽  
Anoop Kanjirakat ◽  
Reza Sadr
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Nano Particles ◽  
Experimental Result ◽  
Tube Heat Exchanger ◽  
Shell And Tube

Innovations in the field of nanotechnology have potential to improve industrial productivity and performance. One promising applications of this emerging technology is using nanofluids with enhanced thermal properties. Nanofluids, engineered colloidal suspensions consisting of nano-sized particles (less than 100nm) dispersed in a basefluid, have shown potential as industrial cooling fluids due to the enhanced heat transfer characteristics. Experiments are conducted to compare the overall heat transfer coefficient and pressure drop of water vs. nanofluids in a laboratory scale industrial type shell and tube heat exchanger. Three mass particle concentrations, 2%, 4% and 6%, of SiO2-water nanofluids are formulated by dispersing 20 nm diameter nano particles in desalinated water. Nanofluid and tap water are then circulated in the cold and hot loops, respectively, of the heat exchanger to avoid direct particle deposition on heater surfaces. Interestingly, experimental result show both augmentation and deterioration of heat transfer coefficient for nanofluids depending on the flow rate through the heat exchangers. This trend is consistent with an earlier reported observation for heat transfer in micro channels. This trend may be explained by the counter effect of the changes in thermo-physical properties of fluids together with the fouling on the heat exchanger surfaces. The measured pressure drop in the nanofluids flow shows an increase when compared to that of basefluid that could limit the use of nanofluids in heat exchangers for industrial application.

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