Thin-walled tube heater for fluid

A method of making a tube heater for heating a fluid in an interior of the tube heater, comprising:

• providing a stainless steel core;
• circumferentially printing a resistive layer on the stainless steel core including electrically insulating the resistive layer with first and second glass layers, one of the glass layers having a thermal conductivity of more than 2 W/mK and the other of the glass layers having a thermal conductivity of less than or equal to 0.5 W/mK;
• and
• arc-spraying aluminum on an inner surface of the stainless steel core.

A method of making a tube heater for heating a fluid in an interior of the tube heater, comprising:

• providing a stainless steel core;
• circumferentially printing a resistive layer on the stainless steel core including electrically insulating the resistive layer with first and second glass layers, one of the glass layers having a thermal conductivity of more than 2 W/mK and the other of the glass layers having a thermal conductivity of less than or equal to 0.5 W/mK;
• and
• providing a mesh stencil over the stainless steel core and leveling through the mesh stencil a paste.

A method of making a tube heater for heating a fluid in an interior of the tube heater, comprising:

• providing a stainless steel core;
• circumferentially printing a resistive layer on the stainless steel core including electrically insulating the resistive layer with first and second glass layers, one of the glass layers having a thermal conductivity of more than 2 W/mK and the other of the glass layers having a thermal conductivity of less than or equal to 0.5 W/mK;
• letting dry the resistive layer;
• and
• providing the resistive layer on the stainless steel core and heating the resistive layer for about 30 minutes with a peak temperature of the heating unit at about 850° C. for at least 5 minutes.

A method of making a tube heater for heating a fluid in an interior of the tube heater, comprising:

• providing a stainless steel core;
• and
• circumferentially printing a resistive layer on the stainless steel core including electrically insulating the resistive layer with first and second glass layers, one of the glass layers having a thermal conductivity of more than 2 W/mK and the other of the glass layers having a thermal conductivity of less than or equal to 0.5 W/mK,
• wherein the providing the stainless steel core includes deep drawing a stainless steel blank through a die.

A method of making a tube heater for heating a fluid in an interior of the tube heater, comprising:

• providing a stainless steel core;
• layering a first glass on the stainless steel core, the first glass being electrically insulative and having a thermal conductivity of more than 2 W/mK;
• patterning a resistive layer on the first glass;
• and
• layering a second glass on the resistive layer, the second glass being electrically insulative and having a thermal conductivity of less than or equal to 0.5 W/mK;
• dimpling an inner surface of the stainless steel core;
• and
• arc spraying aluminum on the dimpled inner surface of the stainless steel core.