Developing rapid heating and cooling systems using pyrolytic graphite

Rapid heating and cooling is desired in many applications. A new type of rapid heating and cooling system using pyrolytic graphite (PG) was investigated. Due to a large degree of anisotropy, a factor of 200 in thermal conductivity difference and a factor of 1200 in electrical resistivity difference, PG is suitable for rapid surface heating. The high electrical resistivity and the low thermal conductivity in the thickness direction provide the electrical and thermal insulation between the surface and the bulk base. The low thermal expansion coefficient about 0.5 x 10(-6) cm/cm/degreesC in the direction parallel to the surface helps maintain mechanical integrity during rapid thermal cycling. Heating and cooling characteristics of PG were studied in both simulation and experiments. The actually constructed heating and cooling system based on PG was able to raise the surface temperature from 50 to 250degreesC in 2 s and cool to 50degreesC in 8 s. (C) 2002 Elsevier Science Ltd. All rights reserved.