Pressure Controlled Heat Pipe Furnace

A typical PCHP furnace (as illustrated in the sketch below) consists of four major components that can be physically detached from each other:

1. 1. Annular heat pipe
   2. Tube furnace
   3. Control cabinet with electronics and pressure monitoring system (not shown)
   4. Computer (not shown)

Typical Pressure Controlled Heat Pipe Furnace

Unlike a conventional heat pipe that is hermetically sealed, the vapor space of the annular heat pipe in the PCHP furnace is connected to a helium gas reservoir. The control system for the helium pressure consists of a pressure transducer, a helium supply and a vacuum pump. The pressure is maintained constant by admitting or removing helium. A series of pressure transducers and solenoid valves are typically used. The power input to the furnace is controlled by a temperature controller whose set point is coupled to the pressure control system.

Data collection and commands are performed by a computer equipped with special software. Constant helium pressure translates into constant vapor pressure and temperature inside the heat pipe. The precision of the temperature control can be an order of magnitude better than that of the pressure control. Spatial temperature uniformity of better than 10mK has been measured.

Specifications:

• Temperature range: 300 – 1,100°C
• Set point stability: ±0.01°C
• Temperature uniformity: ±0.01°C/30 cm
• Orientation: horizontal and vertical
• Heat pipe fluid: Cs, K, Na
• Control gas: helium

Advantages include:

• Precision temperature control to 1100°C
• High product yield
• Turnkey computer controls
• Programmable temperature history
• Precise materials processing

For more information, read our technical paper, A Novel Closed System, Pressure Controlled Heat Pipe Design for High Stability Isothermal Furnace Liner Applications.