Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.

Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Methods to Characterize, Measure, and Simulate Airside Fouling of Air-Cooled Condensers in Air-Conditioners

Mehdi Mehrabi, University of Nebraska - Lincoln


Several researchers have studied the effect of airside fouling on heat exchangers of air conditioning units, but most of them focused on evaporators. The current dissertation research is intended to study the airside fouling effects on field condensers, as well as set a method to test the effect of fouling on new condensers. ^ Using the experimental documents, the effect of reducing the airflow through the condensers is generalized by non-dimensionalizing and combining all available laboratory results. The variation level in the results indicates that in many cases, the generalized relationships provide reasonable predictors of fault effects on systems for which laboratory test results are unavailable. ^ Nine field-fouled condensers, including seven plate fin coils and two spine fin coils, were collected from residential condensing units at the end of their service lives and examined in a test apparatus. The results show that the fouling has a negligible effect on the system performance on most of the coils, and unexpectedly in some cases, the fouling can improve the performance of the system. Effect of cleaning the coils with detergent was negligible on the system performance on most of the coils compared to cleaning with water only, and in some cases, the detergent degraded the performance of the system. ^ To mimic the effect of field fouling on new condensers, a synthetic fouling agent was developed using the fouled coils test results, as well as the test results of different field fouling samples. Different mixtures of dust particles and fibers were examined to find the proper mixture that could mimic the field test dust. To test the effect of the synthetic fouling agent on different units, six heat exchangers including three plate fin coils, two microchannel coils, and one spin fin coil were tested in the test apparatus. The results show that the increase in pressure drop after fouling injection was smallest for spine fin coil and was largest for denser coils. The decrease in heat transfer after injection was largest for denser microchannel coil. For one of the coils, the fouling increased the coil capacity as for some field-fouled coils.^

Subject Area

Architectural engineering|Engineering|Mechanical engineering

Recommended Citation

Mehrabi, Mehdi, "Methods to Characterize, Measure, and Simulate Airside Fouling of Air-Cooled Condensers in Air-Conditioners" (2018). ETD collection for University of Nebraska - Lincoln. AAI10844818.