# Experimental and Theoretical Study of Heat Transfer in a Chilled Ceiling System
## 1 Introduction  
Chilled ceiling systems have been used for space cooling in buildings because of their high efficiency and environmental protection. Compared to convective systems, radiant systems have the potential to provide thermal comfort at lower indoor temperatures for heating and at higher indoor temperatures for cooling. There are numerous studies on the heat transfer performance of a chilled ceiling space system. [PERSON] et al. [1] found that asymmetric radiation and cooling conditions significantly affect the thermal interaction between the human body and radiant surfaces. According to the obtained data, they determined that the magnitude of the thermal interaction between the human body and radiant surfaces is higher under asymmetric radiation conditions compared to symmetric radiation conditions. [PERSON] et al. [2] conducted research on the adaptation of radiant heating and cooling system construction for buildings. [PERSON] et al. [3] performed experimental studies on the heat transfer properties of radiant-cooled walls in a fully conditioned life-size space. They concluded that cooling by radiation is an effective method of providing comfort conditions in the space. [PERSON] et al. 's [4] experimental investigations examined the heat transfer properties of a radiantly cooled wall subjected to forced convection with displacement ventilation. They determined the increase in heat transfer during forced convection. [PERSON] [5] experimentally determined that 67% of the total heat transfer coefficient in a wall-cooling application consists of the radiation heat transfer coefficient, and 33% consists of the convective heat transfer coefficient. Additionally, it was determined that the cooling capacity of the panels with an additional aluminum conductive layer is approximately 21% higher compared to thetraditional classic panel. [PERSON] et al. 's [6] studies demonstrated the effectiveness of model predictive control in improving the energy efficiency of ceiling cooling systems. They modeled the system behavior and optimized it in real time, demonstrating energy savings. [PERSON] et al. [7] performed experimental studies on ceiling cooling systems, investigating the dynamic effect of water flow rate changes in the surface temperature of radiant cold ceiling panels. Their results showed that changes in the water flow rate affect surface temperature, increasing it at lower water flow rates. [PERSON] et al. [8] conducted a literature review of surface heat transfer coefficients for radiant heating and cooling systems. They found greater variation and prediction error in total and convective heat transfer values compared to radiative heat transfer, which had a margin of error of \(\pm\)20%. They investigated how to increase the cooling capacity of open-mounted chilled beam ceiling systems. [PERSON] et al. [9] found that the cooling capacity could be increased by 54% to 80% with an appropriate design. [PERSON] et al. [10] proposed a correlation between heat transfer coefficients and heat flux in radiant ceiling panels based on their experimental work in a climate-controlled test chamber. They conducted an experimental study to determine the cooling capacity of radiant cooling ceiling systems. [PERSON] et al. [11] evaluated the factors that influence the cooling capacity of the system, as well as its impact on energy efficiency and comfort conditions. [PERSON] et al. [12] conducted theoretical and experimental studies on cooling ceiling systems to optimize their energy efficiency and performance. [PERSON] et al. 's [13] theoretical and experimental studies concluded that the heat transfer coefficients between radiant ceilings and the room are influenced by various parameters, including the surface temperature distribution, room heat gains and air movement. [PERSON] et al. [14] explored the use of zigzag walls with asymmetric emissivity to enhance passive daytime radiative cooling (PDRC). By reflecting sunlight and emitting infrared radiation, these walls achieve sub-ambient cooling, reducing energy consumption.