28. 一般蒸汽管路，當管路中有凝水時，波紋管內的液體，因低溫而收縮將閥打開，放出凝水，此種為下列何種袪水器？ (A)浮子式袪水器(Mechanical float traps) (B)感溫式袪水器(Thermostatic traps) (C)熱力式袪水器(Thermodynamic traps) (D)壓力式袪水器(Pressure traps)