Cold radiant air conditioners are increasingly valued for their better thermal comfort and greater energy-saving potential

but their likeliness to condensate and low cooling heat flux negatively affect their engineering applications. By establishing a model of the heat transfer process of a metal radiation panel

the influences of the radiation panel heat exchanger tube spacing on heat transfer performance were analyzed. This study found that when the water supply temperature and flow rate were held constant at 17 °C and 0.3 m/s

respectively

reducing the tube spacing of a 1.2 m × 0.4 m copper tube radiant heat exchange surface from 100 mm to 68 mm resulted in a decrease of 0.58 °C in the average surface temperature and 0.76 °C in the maximum surface temperature of the radiant panel. Additionally

it resulted in a decrease of 3.56% in the temperature homogeneity coefficient and 9.41% in the maximum temperature homogeneity coefficient for a conventional equal tube spacing arrangement. Based on these findings

a total of nine types of radiation panels were designed

including three types of variable tube spacing arrangements with 4

5

and 6 rows. Comparison with the corresponding equal tube spacing arrangement of radiation panels showed that the highest average surface temperature decreased by 0.37

0.56

and 0.36 °C

respectively

and the highest temperature homogeneity coefficient decreased by 19.3%

23.5%

and 30.3%

respectively. This highlights that the variable tube spacing arrangements for heat exchanger tubes lead to a more uniform surface temperature.