Dr. Nanditha K. Hettiarachchi, Fernando K.D.K, Athukorala D.C., Tharaka K.T., Rathnayaka R.M.H.M.

Project Abstract

• In the context of the 2025 Capstone Project, continued the three-year effort by enhancing water-cooled airconditioning technology for tropical and humid climates.

• Addressed major issues of air-cooled systems such as corrosion, unstable refrigerant flow, high energy use, and

short lifespan.

• Integrated a tube-in-tube heat exchanger to achieve better heat transfer and stable system operation.

• Validated the redesigned system through simulations, experiments, and performance testing.

• Achieved an indoor temperature of 17°C, demonstrating strong cooling performance.

• Results showed improved cooling capacity, lower energy consumption, reduced maintenance, and longer

system lifespan.

• The project demonstrates strong potential for future eco-friendly, scalable, high-performance HVAC solutions.

Overview

• Conventional air cooled split AC condenser coils corrode in coastal and industrial air, a water cooled chilled water design limits exposure and improves service life.

• Outdoor units face harsh weather and dust, leading to frequent cleaning and repairs, the chilled water approach reduces routine maintenance needs.

• Air cooled heat rejection weakens as ambient temperature rises, a water cooled condenser with a cooling tower rejects heat more effectively and improves COP.

• Earlier configurations produced limited indoor temperature reduction, the upgraded design aims for stronger and steadier cooling output.

• Split systems are harder to expand and service, chilled water with fan coil units supports modular expansion and simpler maintenance, with less downtime.

• Achieved 17 °C indoor temperature during validation, confirming effective cooling delivery for a single room under realistic operating conditions and typical internal heat loads.

• Delivered 4.7–6.5 kW cooling capacity, demonstrating the system can match and exceed the demand range of a conventional 12,000 BTU room air conditioner.

• Reached COP 3.08–4.26 (average 3.67), indicating strong energy efficiency and competitive performance compared with common non-inverter split air conditioners.

• Integrated water-cooled condenser with cooling tower and tube-in-tube heat exchangers, improving heat rejection, supporting durability, and enabling scalable chilled-water distribution to fan-coil units.