Magnetic field control of cryogenic heat pipes
This paper deals with cryogenic heat pipes controlled by static magnetic field. Heat pipe is an equipment which allows a very effective heat transport. They are commonly used in electronic devices and in many other types of equipment as well. Some applications require heat flow controllability. For that purpose heat pipes are modified to many different constructions with variable heat conductance. Magnetic field control of heat transport is a new solution researched in a few laboratories in the world and still not practically applicated. According to the results of some experiments, implemented in our laboratory and several another laboratories, it seems to be possible to control heat transport in chosen types of heat pipes by a static magnetic field. The cryogenic heat pipe filled with pure oxygen has been made for that purpose and a testing device has been arranged as well. We have found out that the heat transport efficiency of the heat pipe has rapidly decreased by a magnetic field exposure. Some interesting results of our experiments will be presented in this paper.
Control of heat transport in heat pipes by magnetic fields
We have observed that gas flow can be blocked or disturbed by magnetic fields. To explain this phenomenon, we developed a model called a ‘‘magnetic curtain’’ based on the paramagnetic properties of the oxygen molecule. In this paper, we applied this phenomenon to the control of heat transport in heat pipes. We used a heat pipe 20 mm in diameter and 500 mm in length packed with oxygen as a working fluid. We positioned this device vertically in an airgap 70‐mm wide between the poles of electromagnet with 240 mm in diameter, in the direction perpendicular to the axis of the magnetic poles. The top side of the heat pipe was chilled with liquid nitrogen (77 K), and the lower side of the heat pipe was exposed to the room temperature (290 K). The efficiency of heat transport was measured by monitoring the change of the temperature at seven points inside and outside of the heat pipe in response to the step change of the top temperature from 290 to 77 K. When the middle part of the heat pipe was exposed to magneti...
Exopolysaccharide biosynthesis and related enzyme activities of the medicinal fungus, Ganoderma lucidum, grown on lactose in a bioreactor
Exopolysaccharide (EPS) production and biosynthesis were studied in Ganoderma lucidum, a fungus used in traditional Chinese medicine, grown with lactose in a bioreactor. β-Galactosidase activity, which implies the existence of a lactose permease system, was induced by lactose. Lactose feeding also increased α-phosphoglucomutase activity and EPS accumulation but decreased phosphoglucose isomerase activity and lactate concentration in the culture broth. A maximum cell density of 22 g l−1 and EPS at 1.25 g l−1 were obtained in fed-batch bioreactor culture.