Abstract: To investigate harmonic component and corresponding period of heat flux diurnal variation on north wall and back slope in solar greenhouse, the experiment was conducted with Liaoshen GreenhouseⅠunder different conditions with crops and without crops by using Harmonic analysis method. The results showed that diurnal variation curve was composed of sinusoids by π/72, π/36 and π/24 cycles without crops, and by π/72 and π/36 cycles with crops. Crops affected harmonic component and corresponding period significantly. Moreover, investigated harmonic accounted for more than 90%, which indicated that heat flux diurnal variation on north wall and back slope could be expressed by harmonic component during corresponding period, and harmonic analysis could be used to research for heat flux diurnal variation in solar greenhouse.

Key words: Harmonic analysis method, Heat flux, North wall, Back slope, Solar greenhouse