Performance maps for an air-cooled air conditioning system as a preliminary instrument for the diagnosis of evaporator fouling

P Catrini,A Piacentino,A Patil,A L Hjortland,J E Braun

doi:10.1088/1742-6596/1224/1/012024

P Catrini, A Piacentino + Show 3 more

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https://doi.org/10.1088/1742-6596/1224/1/012024

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Abstract

During the past few decades, there has been increased interest in the development of automated approaches for detecting and diagnosing faults in air conditioning systems. Among them, thermoeconomic diagnosis is a technique which involves the use of exergy analysis. As a first step towards improving its performance, this work is focused on the thermodynamic and exergy analysis of a direct expansion air conditioning system used in small commercial building applications. The analysis was carried out by means of experimental activities on a 17.5 kW rooftop unit installed at the Herrick Laboratories, Purdue University, Indiana (USA). The system under investigation was equipped with a variable-speed compressor and variable-speed fans, thus allowing the unit to meet different loads. A detailed mapping of the performance of this system was carried out by considering the effect of the outdoor temperature and the cooling load. In addition, the effect of evaporator fouling was investigated. Results showed that poor exergy performance were achieved due to the exergy destruction occurring in the evaporator. Also, when testing evaporator fouling, results showed that this fault contributed to increase the consumption of the mechanical exergy of the air, thus allowing for an easy detection of this fault.

Highlights

The increase in the global energy demand has been pushing research towards the exploitation of renewable energy sources and towards a more rational use of energy
The unit exergy consumption of refrigerant thermal exergy, i.e. k4,ref is not sensitive to the fault level. These results suggest that detection of evaporator fouling can be achieved only by checking variation in the k4,5 values k1 [Wex/Wex]
This work aims at mapping the exergy performance of a packaged air conditioning unit equipped with a variable speed-fans and variable speed-compressor

Summary

Introduction

The increase in the global energy demand has been pushing research towards the exploitation of renewable energy sources and towards a more rational use of energy To this aim, due to high energy consumption in air conditioning applications, an optimal design and operation of HVAC systems could lead to cost-effective energy savings and environmental benefits. In order to improve the energy performance of these systems, more sophisticated control logics have been implemented, as the variable speed on compressor and fans which allows for a better control of the indoor comfort conditions Another important aspect is the energy consumption during the operation of these systems, which generally increases over time due to poor maintenance [1]. Preliminary details into the exergy behavior of each component and the effects of the control system on the thermoeconomic model adopted are necessary [9]

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