Patent ID: 7886551

Claim:
A humidity control system that includes a refrigerant circuit including a compressor, a first heat exchanger carrying an adsorbent thereon, an expansion valve adjustable in opening and a second heat exchanger carrying an adsorbent thereon and supplies humidity-controlled air to a room by operating alternately in a first batch mode in which the second heat exchanger adsorbs moisture in air and the first heat exchanger releases moisture to air and a second batch mode in which the first heat exchanger adsorbs moisture in air and the second heat exchanger releases moisture to air, the humidity control system comprising: an opening control means that, when a valve control start time has come a predetermined time after the start of each of the first and second batch modes, controls the opening of the expansion valve so that the degree of superheat of refrigerant in the refrigerant circuit reaches a predetermined value, wherein the opening control means is configured to keep the opening of the expansion valve at a fixed value until the valve control start time in each of the first and second batch modes has come.