Open Access

ARTICLE

Analysis of Air Conditioning Unit Performance Due to Variations in Water Cooling Temperature Using an Extra Cooling Water Loop

Noor Moneer Basher¹, Omar Rafae Alomar^1,*, Omar Mohammed Ali², Diyar Abdullah Ahmed³
1 Engineering Technical College of Mosul, Northern Technical University, Cultural Group Street, Mosul, 41002, Iraq
2 College of Mechanical Engineering, University of Zakho, Kurdistan Region, Zakho, 42002, Iraq
3 College of Technical Engineering, Duhok Polytechnic University, Duhok, 42001, Iraq
* Corresponding Author: Omar Rafae Alomar. Email:

Frontiers in Heat and Mass Transfer https://doi.org/10.32604/fhmt.2025.066997

Received 23 April 2025; Accepted 12 September 2025; Published online 13 October 2025

Abstract

The energy consumption of a Split air conditioning unit (ACU) inside a building is extremely large, and efforts to decrease this issue are ongoing. The current work aims to experimentally investigate the thermal performance of ACU using an external cooling-water loop for pre-cooling the condenser to improve the efficiency and to reduce energy consumption by reducing refrigerant temperature before entering the condenser, thereby reducing the coefficient of performance. The experiments are performed on ACU with and without using an external cooling-water loop under different climate conditions. By using the experimental data, the systems’ performances for both cases are evaluated based on the energy, exergy, and pressure drop analysis. Effects of several parameters, e.g., ambient temperature, inlet water temperature, and water volume flow rate, on the energy and exergy performances of ACU systems are presented for the purpose of comparison. The outcomes display that the use of an external cooling water loop system has a significant impact on the system performance as compared to conventional ACU. The results display that the addition of an external cooling-water loop leads to a reduction in the compressor power consumption and to an increase in the coefficient of performance (COP) as compared to a normal ACU. The maximum reduction in compressor power consumption is obtained equal 37% at T_w = 15°C and 11 L/min, whereas the maximum enhancement in COP is obtained equal 21.5% at T_w = 30°C, 11 L/min, and T_amb = 45°C. The modified model shows an increase in exergy efficiency with the maximum enhancement of about 17% at T_w = 30°C and 15.8 L/min. The use of an external cooling water loop leads to a reduction in the irreversibility process of the compressor, evaporator and expansion valve and to an increase in the condenser losses. The outcomes show that the pressure drop is reduced by using a cooling water loop as compared to a normal ACU, where the reduction becomes more evident with a reduction in water volume flow rate and inlet temperature. Finally, the present study reveals that the use of an external cooling water loop system leads to an improvement in the performance of ACUs.

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Keywords

Air conditioning unit; energy; exergy; water heat exchanger; pressure drop; pre-cool condenser

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