Tuesday, 28 June 2016: 11:00 AM-12:30 PM
HVAC Systems and Equipment
Chair:
Raymond Rite, Ph.D., Ingersoll Rand – Trane
Technical Committee: 01.03 Heat Transfer and Fluid Flow
Sponsor: TC 1.13
CoSponsor: 08.04 Air-to-Refrigerant Heat Transfer Equipment
In the quest to reduce energy consumption and the amount of refrigerant in systems, the air-to-refrigerant heat exchanger is a prime area of interest. Although reducing heat exchanger cost and maximizing performance have always been of great interest to the HVAC community, recently new thoughts on tube size, materials, manufacturing processes, as well as computational analysis methodologies have been gaining traction. This program presents all of these facets of modern heat exchanger optimization.
1 Optimization and Validation of Novel Designs for Air-to-Refrigerant Heat Exchangers
 |
Vikrant Aute, University of Maryland |
This work presents a comprehensive optimization and validation of air-to-refrigerant heat exchangers based on novel shapes. The tube hydraulic diameters investigated in this work range from 0.5 to 3 mm. The designs include round as well as non-round tubes. Several optimal designs are prototyped using conventional and additive manufacturing techniques and their performance is measured and compared with the current state-of-the-art heat exchangers. It is shown that for the same performance, the novel designs exhibit significant reductions in heat exchanger size and refrigerant charge. Several manufacturing and application challenges are identified to improve the commercial viability of such novel designs.
2 Numerical Study on Heat Transfer and Pressure Drop Characteristics of Water Cooled Mini-Channel Heat Exchangers
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Man-Hoe Kim, Ph.D., Kyungpook National University |
A numerical investigation of the thermal-hydraulic performance of mini-channel heat exchangers with different fin configurations is presented. Results in terms of pressure drop, base temperature, thermal resistance, and overall heat transfer coefficient were compared for different fin spacing, fin thickness and fin height. In comparison to un-finned geometry, a reduction of 44.8% in base temperature was observed with pressure drop and thermal resistance reductions of 46.5% and 30.4%, respectively. The heat exchanger geometry with the best thermal performance was also simulated for higher heat fluxes within the same operating limits. Results were validated using available correlations and experimental data.
3 Metal Foam Heat Exchanger Design Optimization for Improved Thermal-Hydraulic Performance under Dry Operating Conditions
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Kashif Nawaz, Ph.D., Johnson Controls, Inc. |
Open cell metal foams have received attention for utilization in thermal applications including electronics cooling and HVAC&R. Despite manufacturing and cost-related issues, such novel materials hold promise due to better heat transfer compared with conventional fin designs. However, one of the major issues is their higher air-side pressure drop. Four types of aluminum foam heat exchangers with different pore sizes have been built and tested under dry conditions for this study. The data have been reduced to correlate the foam geometry to air-side heat transfer and pressure drop. These correlations were used to optimize the foam geometry for thermal-hydraulic performance.