Local Nusselt number and temperature field distribution within the compound duct with gap have been measured. Measurement of air and wall temperature span a range of gap width from 2mm to 6mm. Also, the Reynolds number is variated from 20,000 to 40,0000. In order to observe the correlations between gap width and turbulent heat transfer, the present measurement has tried to verify the enhancement effect of heat transfer when a gap exists within the compound channel. From this measurement, we could see that the pulsating flow has generated a strong turbulent flow mixing within the compound channel. And the turbulent flow mixing in the pulsating flow plays an effective role of enhancing the Nusselt number by making the fluid temperature uniformly within the compound channel.

In the present study, we developed optimal heat supply algorithm which minimizes the heat loss through the distribution pipe line in group energy apartment. Heating load variation of group energy apartment building in accordance with outdoor air temperature was predicted by the correlation obtained from calorimeter measurements of whole households of apartment building. Supply water temperature and mass flow rate were conjugately controlled to minimize the heat loss rate through distribution pipe line. Group heating apartment located in Hwaseong city, Korea, which has 1,473 households divided in 4 regions, was selected as the object apartment for verifying the present heat supply control algorithm. Compared to the original heat supply system, 10.4% heat loss rate reduction can be accomplished by employing the present control algorithm.

Ground source heat pumps are clean, energy-efficient and environment-friendly systems. Although the initial cost of ground source heat pump system is higher than that of air source heat pump, it is now widely accepted as an economical system since the installation cost can be returned within an short period of time due to its high efficiency. In the present study, performances of ground source compound hybrid heat pump system applied to a resort building are simulated. The system design and operation process appropriate for the surrounding circumstance guarantee the high benefit of the heat pump system applied to a resort building. If among several renewable energy sources, ground, river, sea, waste water source are chosen as available alternative energies are combined, COP of the system can be increased largely and hybrid heat pump system can reduced the fuel cost.