A dryer (100), comprising a dryer chamber (101) coupled to a closed loop gas-circulating system for circulating gas through the dryer chamber (101); wherein the closed loop gas-circulating system recirculates the gas and comprises: a compressor (113) coupled to receive return gas from the dryer chamber (101) and to compress the return gas to provide compressed gas; a separator (109) sitting in the gas-circulating system for draining condensate from the gas; and a gas discharger (103; 104) coupled to receive compressed gas from the compressor (113) and to discharge the compressed gas through a discharger exit (118). The separator sits in the closed loop gas-circulating system downstream of the compressor to receive compressed gas and upstream of the gas discharger (103;104). Thereby drying efficacy is improved and is advantageous at relatively low drying temperatures such as below 40 degrees Celsius. There is also provided a door for a dryer, a method of operating a dryer and a method of drying, such as a method of drying pharmaceutical substances, compounds, ingredients or products.