Multi-passage electric heater using ceramic foam as a diffuser and method of use

Abstract

A multi-passage electric heater for heating a gas flowing through the passages uses electric heating elements disposed in the passages for gas heating. One of both of the inlet and outlet of the heater includes a ceramic foam material as a diffuser. The diffuser on the inlet side effectively distributes gas evenly to the passages for heating and insulates against radiated heat loss through the inlet. When located on the outlet side of the heater, a more homogenous outlet stream of heated gas is created, with the outlet diffuser minimizing loss of radiated heat from the outlet side and acting as a heat exchange medium for improved heater efficiency.

1 . In a multi-passage electric heater having a heater core, an inlet and an outlet, wherein at least some of passages of the heater core each include an electric heater for heating a gas passing therethrough, the improvement comprising a ceramic foam material placed over at least a portion of one or both of the inlet and the outlet of the heater. 
   
   
       2 . The heater of  claim 1 , wherein the ceramic foam material is placed over both the inlet and the outlet of the heater. 
   
   
       3 . The heater of  claim 1 , wherein the heater inlet and outlet are circular in shape, and the ceramic foam material is in the form of a disk. 
   
   
       4 . The heater of  claim 1 , wherein the ceramic foam diffuser covers an entirety of the inlet or the outlet or both. 
   
   
       5 . The heater of  claim 2 , wherein the ceramic foam material covers an entirety of the inlet or the outlet or both. 
   
   
       6 . The heater of  claim 1 , wherein the ceramic foam material is mounted to a housing of the heater to cooperate with the housing as a stop against movement of the heater core during operation. 
   
   
       7 . The heater of  claim 1 , wherein the ceramic foam is a magnesia-stabilized zirconia ceramic foam. 
   
   
       8 . The heater of  claim 2 , wherein the ceramic foam material is mounted to a housing of the heater to cooperate with the housing as a stop against movement of the heater core during operation. 
   
   
       9 . The heater of  claim 1 , wherein the heater further comprises a gas inlet tube for directing incoming gas to the heater core, the ceramic foam material being positioned between the gas inlet tube and heater core as an inlet diffuser, the inlet diffuser further positioned to form a gap between an upstream face of the inlet diffuser and an outlet of the gas inlet tube to facilitate distribution of incoming gas to the upstream face of the inlet diffuser. 
   
   
       10 . In a method of heating a gas using a multi-passage electric heater having a heater core, an inlet and an outlet, and wherein at least some of passages of the heater core each include an electric heater for heating gas passing therethrough, the improvement comprising placing a ceramic foam material over at least a portion of one or both of the inlet and outlet to minimize radiation from the heater and to either distribute the gas entering the heater or exiting the heater. 
   
   
       11 . The method of  claim 10 , wherein the ceramic foam material is placed over each of the inlet and outlet. 
   
   
       12 . The method of  claim 10 , wherein the ceramic foam material is placed over an entirety of either the inlet or the outlet or both. 
   
   
       13 . The method of  claim 11 , wherein the ceramic foam material is placed over an entirety of either the inlet or the outlet or both. 
   
   
       14 . The method of  claim 10 , wherein the ceramic foam material is mounted to a housing of the heater so as to cooperate with the housing as a stop against movement of the heater core during heater operation. 
   
   
       15 . The method of  claim 10 , wherein the ceramic foam material is used as an inlet diffuser, and further forming a gap adjacent an upstream face of inlet diffuser in the heater to facilitate distribution of incoming gas to the upstream face of the inlet diffuser.