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Title: Miniaturized Air-to-Refrigerant Heat Exchangers

Abstract

Air-to-refrigerant Heat eXchangers (HX) are an essential component of Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) systems, serving as the main heat transfer component. The major limiting factor to HX performance is the large airside thermal resistance. Recent literature aims at improving heat transfer performance by utilizing enhancement methods such as fins and small tube diameters; this has lead to almost exhaustive research on the microchannel HX (MCHX). The objective of this project is to develop a miniaturized air-to-refrigerant HX with at least 20% reduction in volume, material volume, and approach temperature compared to current state-of-the-art multiport flat tube designs and also be capable of production within five years. Moreover, the proposed HX’s are expected to have good water drainage and should succeed in both evaporator and condenser applications. The project leveraged Parallel-Parametrized Computational Fluid Dynamics (PPCFD) and Approximation-Assisted Optimization (AAO) techniques to perform multi-scale analysis and shape optimization with the intent of developing novel HX designs whose thermal-hydraulic performance exceeds that of state-of-the-art MCHX. Nine heat exchanger geometries were initially chosen for detailed analysis, selected from 35+ geometries which were identified in previous work at the University of Maryland, College Park. The newly developed optimization framework was exercised for threemore » design optimization problems: (DP I) 1.0kW radiator, (DP II) 10kW radiator and (DP III) 10kW two-phase HX. DP I consisted of the design and optimization of 1.0kW air-to-water HX’s which exceeded the project requirements of 20% volume/material reduction and 20% better performance. Two prototypes for the 1.0kW HX were prototyped, tested and validated using newly-designed airside and refrigerant side test facilities. DP II, a scaled version DP I for 10kW air-to-water HX applications, also yielded optimized HX designs which met project requirements. Attempts to prototype a 10kW have presented unique manufacturing challenges, especially regarding tube blockages and structural stability. DP III comprised optimizing two-phase HX’s for a 3.0Ton capacity in a heat pump / air-conditioning unit for cooling mode application using R410A as the working fluid. The HX’s theoretically address the project requirements. System-level analysis showed the HX’s achieved up to 15% improvement in COP while also reducing overall unit charge by 30-40%. The project methodology was capable of developing HX’s which can outperform current state-of-the-art MCHX by at least 20% reduction in volume, material volume, and approach temperature. Additionally, the capability for optimization using refrigerant charge as an objective function was developed. The five-year manufacturing feasibility of the proposed HX’s was shown to have a good outlook. Successful prototyping through both conventional manufacturing methods and next generation methods such as additive manufacturing was achieved.« less

Authors:
 [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2]
  1. Univ. of Maryland, College Park, MD (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
OSTI Identifier:
1358252
Report Number(s):
DOE-UMD-EE-00006114
DOE Contract Number:
EE0006114
Resource Type:
Technical Report
Resource Relation:
Related Information: D. Bacellar, V. Aute, O. Abdelaziz, R. Radermacher, Design of Novel Air-to-Refrigerant Heat Exchangers Using Approximation Assisted Optimization, in ASME 2014 Verification & Validation Symposium, Las Vegas, NV, USA, May 7-9, 2014.D. Bacellar, V. Aute, R. Radermacher, CFD-Based Correlation Development for Air Side Performance of Finned and Finless Tube Heat Exchangers with Small Diameter Tubes, 15th International Refrigeration and Air Conditioning Conference, Purdue University, West Lafayette, IN, USA, July 14-17, 2014.D. Bacellar, J. Ling, O. Abdelaziz, V. Aute, R. Radermacher, Multi-Scale Modeling and Approximation Assisted Optimization of Bare Tube Heat Exchangers, Proceedings of the 15th International Heat Transfer Conference, IHTC-15, Kyoto, Japan, August 10-15, 2014.D. Bacellar, O. Abdelaziz, V. Aute, R. Radermacher, Novel Heat Exchanger Design using Computational Fluid Dynamics and Approximation Assisted Optimization, ASHRAE 2015, Winter Conference, Chicago, IL, USA, January 24-28, 2015.D. Bacellar, V. Aute, R. Radermacher, A Method for Air-To-Refrigerant Heat Exchanger Multi-Scale Analysis and Optimization with Tube Shape Parameterization, 24th IIR International Congress of Refrigeration, Yokohama, Japan, August 16-22, 2015.D. Bacellar, V. Aute, Z. Huang, R. Radermacher, Multi-Scale Analysis and Shape Optimization Method for High Performance Compact Air-to-Fluid Heat Exchangers Design (Submitted to the International Journal of Heat and Mass Transfer).D. Bacellar, V. Aute, R. Radermacher, Novel Airside Heat Transfer Surface Designs using an Integrated Multi-Scale Analysis with Topology and Shape Optimization, 16th International Refrigeration and Air Conditioning Conference, Purdue University, West Lafayette, IN, USA, July 11-14, 2016.D. Bacellar, V. Aute, Z. Huang, R. Radermacher, Airside Performance Correlations and Optimal Heat Pump Heat Exchanger Designs Based on 0.5mm-2mm Finless Round Tube Bundles, 16th International Refrigeration and Air Conditioning Conference, Purdue University, West Lafayette, IN, USA, July 11-14, 2016.
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; heat exchangers; refrigerant; evaporator; condenser; optimization; HVAC; radiator; approximation; CFD; multiscale; genetic algorithms; air-to-refrigerant; microchannel HX

Citation Formats

Radermacher, Reinhard, Bacellar, Daniel, Aute, Vikrant, Huang, Zhiwei, Hwang, Yunho, Ling, Jiazhen, Muehlbauer, Jan, Tancabel, James, Abdelaziz, Omar, and Zhang, Mingkan. Miniaturized Air-to-Refrigerant Heat Exchangers. United States: N. p., 2017. Web. doi:10.2172/1358252.
Radermacher, Reinhard, Bacellar, Daniel, Aute, Vikrant, Huang, Zhiwei, Hwang, Yunho, Ling, Jiazhen, Muehlbauer, Jan, Tancabel, James, Abdelaziz, Omar, & Zhang, Mingkan. Miniaturized Air-to-Refrigerant Heat Exchangers. United States. doi:10.2172/1358252.
Radermacher, Reinhard, Bacellar, Daniel, Aute, Vikrant, Huang, Zhiwei, Hwang, Yunho, Ling, Jiazhen, Muehlbauer, Jan, Tancabel, James, Abdelaziz, Omar, and Zhang, Mingkan. 2017. "Miniaturized Air-to-Refrigerant Heat Exchangers". United States. doi:10.2172/1358252. https://www.osti.gov/servlets/purl/1358252.
@article{osti_1358252,
title = {Miniaturized Air-to-Refrigerant Heat Exchangers},
author = {Radermacher, Reinhard and Bacellar, Daniel and Aute, Vikrant and Huang, Zhiwei and Hwang, Yunho and Ling, Jiazhen and Muehlbauer, Jan and Tancabel, James and Abdelaziz, Omar and Zhang, Mingkan},
abstractNote = {Air-to-refrigerant Heat eXchangers (HX) are an essential component of Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) systems, serving as the main heat transfer component. The major limiting factor to HX performance is the large airside thermal resistance. Recent literature aims at improving heat transfer performance by utilizing enhancement methods such as fins and small tube diameters; this has lead to almost exhaustive research on the microchannel HX (MCHX). The objective of this project is to develop a miniaturized air-to-refrigerant HX with at least 20% reduction in volume, material volume, and approach temperature compared to current state-of-the-art multiport flat tube designs and also be capable of production within five years. Moreover, the proposed HX’s are expected to have good water drainage and should succeed in both evaporator and condenser applications. The project leveraged Parallel-Parametrized Computational Fluid Dynamics (PPCFD) and Approximation-Assisted Optimization (AAO) techniques to perform multi-scale analysis and shape optimization with the intent of developing novel HX designs whose thermal-hydraulic performance exceeds that of state-of-the-art MCHX. Nine heat exchanger geometries were initially chosen for detailed analysis, selected from 35+ geometries which were identified in previous work at the University of Maryland, College Park. The newly developed optimization framework was exercised for three design optimization problems: (DP I) 1.0kW radiator, (DP II) 10kW radiator and (DP III) 10kW two-phase HX. DP I consisted of the design and optimization of 1.0kW air-to-water HX’s which exceeded the project requirements of 20% volume/material reduction and 20% better performance. Two prototypes for the 1.0kW HX were prototyped, tested and validated using newly-designed airside and refrigerant side test facilities. DP II, a scaled version DP I for 10kW air-to-water HX applications, also yielded optimized HX designs which met project requirements. Attempts to prototype a 10kW have presented unique manufacturing challenges, especially regarding tube blockages and structural stability. DP III comprised optimizing two-phase HX’s for a 3.0Ton capacity in a heat pump / air-conditioning unit for cooling mode application using R410A as the working fluid. The HX’s theoretically address the project requirements. System-level analysis showed the HX’s achieved up to 15% improvement in COP while also reducing overall unit charge by 30-40%. The project methodology was capable of developing HX’s which can outperform current state-of-the-art MCHX by at least 20% reduction in volume, material volume, and approach temperature. Additionally, the capability for optimization using refrigerant charge as an objective function was developed. The five-year manufacturing feasibility of the proposed HX’s was shown to have a good outlook. Successful prototyping through both conventional manufacturing methods and next generation methods such as additive manufacturing was achieved.},
doi = {10.2172/1358252},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 5
}

Technical Report:

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  • The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, this RF appears to provide energy savings of 24%, compared to current U.S. RF designs. The NARMs modeled with the best performance included R-32/-152a, R-22/-142b, and R-32/-142b. An 18% improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6% improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. The advantages ofmore » the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles.« less
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The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air enthalpy method where relevant air-side parameters were controlled while collecting output performance data at discreet points of steady-state operation. The primary metrics include system power consumption and zonal heating and cooling capacity. Using this test method, the measured total cooling capacity was somewhat lower than reported by the manufacturer. The measured power was found to be equal to or greater than the manufacturers indicated power. Heating capacity measurements produced similar results. The air-side performance metric was total cooling and heating energy since the computer model uses those same metrics as input to the model. Although the sensible and latent components of total cooling were measured, they are not described in this report. 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