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Miniaturized Air to Refrigerant Heat Exchangers

Credit: Oak Ridge National Lab

Credit: Oak Ridge National Lab

(a) Finned Microchannel (MCHX);<br />
(b) Web-Tube (WTHX) (Abdelaziz et. al., 2010); <br />
(c) Round Bare Tube (BTHX);<br />
(d) Plain Fin-and-Tube (FTHX).<br />
Credit: Oak Ridge National Lab

(a) Finned Microchannel (MCHX);
(b) Web-Tube (WTHX) (Abdelaziz et. al., 2010);
(c) Round Bare Tube (BTHX);
(d) Plain Fin-and-Tube (FTHX).
Credit: Oak Ridge National Lab

Credit: Oak Ridge National Lab
(a) Finned Microchannel (MCHX);<br />
(b) Web-Tube (WTHX) (Abdelaziz et. al., 2010); <br />
(c) Round Bare Tube (BTHX);<br />
(d) Plain Fin-and-Tube (FTHX).<br />
Credit: Oak Ridge National Lab

Lead Performer: University of Maryland - College Park, MD
Partners:
-- Oak Ridge National Laboratory - Oak Ridge, TN
-- Luvata - Grenada, MS
-- International Copper Association - New York, NY
-- Wieland - Ulm, Germany
-- Heat Transfer Technologies - Abington, PA
DOE Funding: $1,500,000
Cost Share: N/A
Project Term: 3/1/2013 - 2/29/2016
Funding Opportunity: Energy Savings Through Improved Mechanical Systems and Building Envelope Technologies 2012 (DE-FOA-0000621)

Project Objective

This project is developing a miniaturized air-to-refrigerant heat exchanger that is more compact and more energy efficient than current market designs. The heat exchanger will feature at least 20% less volume, material volume, and approach temperature compared to current multiport flat tube designs, and it will be in production within five years. The heat exchanger, which acts as both an evaporator and a condenser, can be applied to commercial and residential air-conditioning or heat pump systems with various capacity scales. Prototype 1-kilowatt (kW) and 10 kW designs will be tested and then improved as necessary for final tests and demonstration in a 3-ton heat pump.

Project Impact

Heat exchangers play a vital role in HVAC&R equipment. They provide means to exchange heat to provide heating or cooling, as well to reject or absorb heat from ambient. For decades, the HVAC&R industry have used tube-fin heat exchangers; however, they just started transitioning to multi-port flat tubes, also known as microchannel heat exchangers. The development of microchannel heat exchangers and introduction in the HVAC&R industry took more than 20 years due to challenges in water drainage, fouling, and perceived risks by design engineers. This project aims at developing the next generation of air-to-refrigerant HX that would improve the heat transfer, reduce pressure drop, increase robustness, and improve cost competitiveness. A recent study (Westphalen et al. 2006) shows a potential of 0.7 to 1.1 quads of energy offset just by increasing the condensing units' Heat Transfer Coefficient (HTC) by 100% in the U.S. market.

References:
Westphalen, D., Roth, K. W. and Brodrick, J. (2006) 'Heat transfer enhancement', ASHRAE Journal, 48(4), 68-71.

Contacts

DOE Technology Manager: Tony Bouza
Performer: Reinhard Radermacher, University of Maryland

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