Devices and methods for controlling a fluid module

A cooling module 103 for use in a fuel cell system 101 comprises first 204 and second 212 chambers containing first 208 and second 216 materials. The second chamber at least partially surrounds the first chamber and an insulating material 220 separates the chambers. Upon a decrease in ambient temperature, the second material freezes before the first material. The first and second material may be water or an exothermic gel and the materials may be different or the same. Second insulation 224 may surround the module. At least one heating. A bimetallic switch temperature sensor (120) connected to a controller (110) may control at least one heating element (112, fig 2) that is in fluid contact with one or both of the materials. The heating element may be an electrical resistance heater or exhaust from the fuel cell system. A strain gauge (124, fig 4) and float (128) may detect quantity of material frozen, and a pressure sensor (126. fig 4) may detect pressure changes of the materials. During changes of state of the materials, the second chamber may expand and contract without cracking. A method of delaying the freezing of the first material is also disclosed.