Experimental study of an air-conditioned tractor cabin using CFD analysis for primary and secondary tillage operations in Pakistan

• Tested tractor cabin provides thermal comfort during tillage operations • Cabin interior temperatures reduces up to 12.9°C compared to ambient conditions • CFD analysis showed that higher AC vents’ air velocity resulted suitable PMV index Provision of thermal comfort for tractor operators is crucial due to extreme weather conditions in agricultural fields. It becomes more complex due to higher heat loads entering the cabin from the engine during tillage operations, increasing cabin temperature and air-conditioning loads. However, no previous studies were found assessing thermal comfort for tractor operators during tillage operations specific to Pakistan. Therefore, an air-conditioning (AC) cabin was designed, developed, and tested with computational fluid dynamics (CFD) simulation in the previous study. In this study, the experiments and CFD analyses are further expanded for various tillage operations including road marching. AC performance of the cabin was evaluated using criteria defined in ISO standards and relevant literature. CFD simulations were performed to assess the impact of incoming air temperature, relative humidity, and velocity on operator's thermal comfort. Experimental results showed that the maximum temperature differences (ΔT) between outside and inside cabin air during parking (12.9°C), marching (11.7°C), rotavating (11.8°C), and chisel plowing (11.8°C) met the ISO thermal comfort criteria. Maximum uncertainties in temperature and relative humidity measurement were calculated as ±0.32°C and ±5%, respectively, showing acceptable error in measurements. The CFD results showed that every 5°C increase in incoming air temperature led to increase inside cabin air temperature by 3.6°C. However, higher incoming air velocity (i.e., 8 m/s) from air-conditioner vents can provide thermal comfort to the operator even at higher temperatures. Therefore, it is recommended to consider operators’ responses to better evaluate the thermal comfort inside the cabin.