Session: 01-01: Decarbonizing Industrial Processes

Paper Number: 166353

166353 - Application of Radiant Cooling Coatings in Air Conditioning Package Units 

Abstract: 

Industrial HVAC systems account for approximately 20–40% of global energy consumption, contributing significantly to the total global energy demand of around 180,000,000 GWh per year. Out of this, HVAC systems alone consume an estimated 36,000,000 to 72,000,000 GWh annually. Improving their efficiency is essential for reducing operational costs and environmental impact. The solution proposed in this article is the application of radiant cooling paint with calcium carbonate (CaCO₃) microspheres base, which can enhance cooling performance by reflecting some of the sunlight in the infrared spectrum as well and cools the surface to sub-ambient temperatures effectively. This study explores the use of CaCO₃ microspheres in cooling paint coatings applied to the external surfaces of package HVAC units to reduce the temperature of air entering the evaporator tubes, thereby lowering the overall thermal load on the system.

Calcium carbonate microspheres are highly effective due to their unique structural properties, which include high solar reflectivity, low thermal conductivity, and enhanced radiative cooling performance. These microspheres improve the paint’s ability to scatter infrared radiation and reflect a greater portion of incident sunlight, thereby minimizing heat absorption by the HVAC unit’s outer surfaces. Additionally, their porous nature facilitates radiative cooling by emitting absorbed heat in the mid-infrared spectrum, helping maintain lower surface temperatures. As a result, the air surrounding the HVAC system remains cooler, reducing the compressor workload and energy demand.

This study combines experimental testing and computational simulations to analyze the impact of CaCO₃ microsphere-based cooling paint on HVAC system performance. The results demonstrate a significant decrease in external surface temperatures and a reduction in intake air temperature before reaching the evaporator tubes. This leads to an improvement in the coefficient of performance (COP) of the package units, allowing the system to operate more efficiently with lower electricity consumption.

The benefits of this approach are particularly evident in hot climate conditions, where solar exposure and high ambient temperatures contribute to excessive cooling loads. By easing on the external heat gain of HVAC units, CaCO₃ microsphere-based coatings provide a cost-effective and sustainable cooling solution for industrial and commercial applications. Additionally, the reduced energy demand translates to a lower carbon footprint, supporting global sustainability efforts and energy efficiency initiatives.

This article covers direct and indirect application methods of these coatings. In In-direct method a cooling panel is developed and used to produce sub-ambient water through passive cooling, which is utilized in chamber of evaporator ducts along with the insulations as well. The findings of In-direct application has provided better results when compared to the direct application.

Beyond performance improvements, this paper also examines the practical aspects of implementing CaCO₃ microsphere coatings in large scale industrial or residential HVAC applications, including material durability, ease of application, maintenance, and cost-effectiveness. The application procedure provides long term resilience when blended with acrylic substrates. Compared to traditional cooling technologies, this passive cooling strategy requires no major system modifications, making it a scalable and economically viable option for widespread adoption.

In conclusion, the integration of CaCO₃ microsphere-enhanced radiant cooling paint has shown great potential in passively reducing heat intake and cooling air before it enters the evaporator tubes of package HVAC units. Given the enormous energy footprint of industrial HVAC systems, widespread implementation of this cooling strategy could result in substantial global energy savings. As industries and commercial sectors seek innovative solutions for energy optimization, the use of high-reflectivity and radiative cooling coatings represents a simple yet highly effective method for improving HVAC efficiency, lowering operational costs, and mitigating environmental impact. Future research should focus on optimizing microsphere formulations, assessing long-term performance across diverse climatic conditions, and exploring synergies with other passive cooling technologies to further enhance energy efficiency in HVAC systems.

Presenting Author: Umair Hasnain Atlas Autos PVT Limited

Presenting Author Biography: The Lead Author is Manufacturing Engineer with 17+ Years of Industry Experience in the fields of Facility Designing and Commissioning, Desiging of HVAC systems, Compressed Air Systems, Process Heating/Cooling Systems, Power Generation and Heat Recovery systems. The Author has experience in areas of Projects Designing & Commissioning and Facility Operations & Maintenance. His experience and contributions in the field have been appreciated and recognized by a number of Industry experts.