Expansion tank with membrane thermal protection

Abstract

An expansion tank for accommodating hot expanded fluid in a heat transfer fluid system has a tank body defining an internal volume. A fluid inlet is provided on the tank body for connection to the heat transfer fluid system. A membrane, such as a diaphragm or a bladder, divides the internal volume into first and second sections. The first section includes a buffer zone between the fluid inlet and the membrane. The buffer zone contains a predetermined volume of tempering fluid for cooling down the incoming hot expanded fluid at its entry in the expansion tank. The buffer zone has an air valve for venting air from the buffer zone while the buffer zone is being filled up with the tempering fluid. The second section on the opposed side of the membrane is maintained under pressure with a gas.

What is claimed is: 
     
         1 . An expansion tank for accommodating hot expanded fluid in a heat transfer fluid system, the expansion tank comprising a tank body having an internal volume, a fluid inlet provided on the tank body and adapted to be connected to the heat transfer fluid system, a membrane mounted within said tank body for dividing said internal volume into first and second sections, said first section including a buffer zone between the fluid inlet and the membrane, the buffer zone containing a predetermined volume of tempering fluid for cooling down any incoming hot expanded fluid at its entry in the expansion tank, the buffer zone having an air valve provided at an upper end thereof for venting air from the buffer zone while the buffer zone is being filled up with the tempering fluid, the second section on the opposed side of the membrane being filled up with a pressurized fluid, the second section of the internal volume having a valve for allowing the second section to be maintained at a predetermined pressure. 
     
     
         2 . The expansion tank defined in  claim 1 , wherein the tank body comprises first and second shell members, each of said first and second shell members having an end wall and a tubular side wall, said first and second shell members being assembled together with respective end walls in opposed facing relationship, and wherein the tank body further comprises a third shell member installed over said first shell member, said buffer zone being defined between said third and first shell members, the second section of the internal volume being bounded by the membrane, the first shell and the second shell. 
     
     
         3 . The expansion tank defined in  claim 2 , wherein the fluid inlet and the air valve are both provided on said third shell member, and wherein the membrane is provided in the form of a bladder mounted in an inlet hole defined in the end wall of the first shell member, the bladder being in fluid flow communication with the buffer zone and expandable in the second section of the internal volume between the first and second shell members. 
     
     
         4 . The expansion tank defined in  claim 2 , wherein the valve for maintaining the second section at a predetermined pressure is mounted to one of the first and second shell members. 
     
     
         5 . The expansion tank defined in  claim 1 , wherein the fluid inlet includes a diffuser for diffusing incoming hot expanded fluid into the tempering fluid contained in the buffer zone. 
     
     
         6 . The expansion tank defined in  claim 1 , wherein the tank body comprises a generally cylindrical housing having a side wall and opposed end walls, and a shell member having one end wall and a side wall extending from the end wall, the shell member being mounted over the housing, the buffer zone being defined between the shell member and the housing, the membrane being mounted within the housing and communicating with the buffer zone via an opening defined in one of the end walls of the housing. 
     
     
         7 . An expansion tank for use in a heat transfer fluid system, the expansion tank comprising a shell defining an internal volume, a membrane dividing said internal volume into a gas chamber and an expandable fluid receiving chamber, a fluid opening provided on said shell and communicating with said expandable fluid receiving chamber, a closable gas inlet provided on said shell and communicating with said gas chamber for allowing a pressurized gas to be directed and maintained under pressure in said gas chamber, a shell extension member mounted over one end of the shell to define therewith a thermal buffer chamber adapted to be filled with a tempering fluid, said thermal buffer chamber communicating with said expandable fluid receiving chamber via said fluid opening, an air valve provided on said shell extension member to allow air to be expelled from the thermal buffer chamber while the same is being filled up with the tempering fluid, and an inlet port provided on the shell extension member and connectable to the heat transfer fluid system, the thermal buffer being disposed between the inlet port and the fluid opening of the first shell member, whereby hot expanded fluid from the system mixes with the tempering fluid contained in the thermal buffer chamber at its entry in the expansion tank, the hot expanded fluid being cooled down by the tempering fluid. 
     
     
         8 . The expansion tank defined in  claim 7 , wherein the volume of the thermal buffer section is sufficient to cool down the hot expanded fluid to a temperature which is inferior to a maximum temperature that the membrane is able to withstand. 
     
     
         9 . The expansion tank defined in  claim 7 , wherein the shell comprises first and second shell members, each of said first and second shell members having an end wall and a tubular side wall, the first and second shell members being assembled together with respective end walls in opposed facing relationship. 
     
     
         10 . The expansion tank defined in  claim 9 , wherein the fluid opening is defined in the end wall of the first shell member, and wherein the shell extension member is mounted over the first shell member. 
     
     
         11 . The expansion thank defined in  claim 7 , wherein the air valve is disposed at an upper end of the thermal buffer chamber. 
     
     
         12 . The expansion tank defined in  claim 7 , wherein the fluid inlet includes a diffuser for diffusing incoming hot expanded fluid into the thermal buffer chamber. 
     
     
         13 . The expansion tank defined in  claim 7 , wherein the membrane is provided in the form of a bladder extending from said fluid opening, the bladder being in fluid flow communication with the thermal buffer chamber.