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Airside performance correlations and optimal air-conditioning heat exchanger designs based on 0.5mm-2mm finless round tube bundles.

Number: pap. 2118

Author(s) : BACELLAR D., AUTE V., RADERMACHER R.

Summary

The use of small diameter tubes in air-to-refrigerant heat exchangers has significant advantages, which include increase in heat transfer coefficient, reduction in size, reduction in material or weight and reduction in refrigerant charge. However, there are no airside correlations for small diameter tubes below 2.0mm in the literature. Furthermore, conventional empirical correlation development relies on testing of samples, which is inherently time consuming, expensive and has a limited range of applicability. This paper presents equations for airside friction and heat transfer characteristics for bare tube air-to-refrigerant Heat eXchangers (HX) with tube diameters ranging from 0.5mm to 2mm, and are valid for 2 to 40 rows of tubes in both staggered and inline arrangements. The correlations presented in this article are developed based on comprehensive CFD simulations for a large design space and include experimental validation. More than 80% of source data can be predicted within 10% error and more than 90% within 20% error. In this paper we use these correlations to optimize the condenser and evaporator of a 3 ton air-conditioning unit using R410A as the working fluid. The HX optimization framework uses a Multi-Objective Genetic Algorithm (MOGA) and an in-house HX design tool based on a segmented e-NTU method. The ultimate goal of optimizing these HX’s is to obtain better system performance. Therefore, the HX optimization targets the reduction of thermal resistance resulting in a smaller approach temperature and reduced pressure lift. A theoretical analysis showed that the maximum COP improvement is of 29%, however a 10% improvement is possible with realistic approach temperatures. The optimum HX’s not only deliver the higher COP but are at least 50% more compact, 80% less material volume, have smaller face areas and reduced the overall system charge in 20%.

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Pages: 10 p.

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Details

  • Original title: Airside performance correlations and optimal air-conditioning heat exchanger designs based on 0.5mm-2mm finless round tube bundles.
  • Record ID : 30018717
  • Languages: English
  • Source: 2016 Purdue Conferences. 16th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2016/07/11

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