In Figs. 2 and 3, points Tinlet and Texit represent the inlet and outlet of the buried pipe of the earth–pipe–air heat exchanger system respectively.
Fig. 2 represents the comparison of the results of the simulation and experiments for air velocities of 2.0, 3.2, 4.0 and 5.0 m/s at the outlet of the steel and PVC pipes respectively.
Tables 2 and 3 show the validation of simulated temperatures with experimental results.
This is apparent that variation in simulated and experimental results ranges from 0 to 11.4% of experimental results.
This variation may occur due to the variation in coefficient of friction of engineering material used in simulation and experiment, irregularities such as joints in experimental set-up and improper insulation at the risers of experimental set-up