The database (DB) on organic composites and organic materials for cryogenic use has been established and the usage of the DB is described. There are two characteristics of the DB, that is (i) only the measured data are accumulated, and (ii) the name of the suppliers and the trade names are considered as one of the specifications of the material. The problems originated from the different measuring methods which exist potentially in DB can be avoided. The user of the DB can obtain easily the materials accumulated in the DB because the trade names or the suppliers names are described. The DB will be supplied in the form of floppy disk in which data are accumulated using the commercially available software. The data which do not exist in the DB can be obtained using the measuring systems installed in the laboratory.
Thermoacoustic theory gives two types of heat flux. One is proportional to thermal expansion coefficient of working fluid and contributes to heat-pumping effect of cryocoolers. The other is proportional to the heat capacity and axial gradient of temperarture. This acoustically enhanced heat-conduction term corresponds to one of regenerator losses, shuttle loss of displacer and a part of heat-flux in conventional “Dream Pipe.” Heat transports in the “Dream Pipe” are discussed in terms of thermoacoustics of inviscid fluid. Results of thermoacoustic theory are compared with experiments of dream pipe of which working fluid is liquid water. Good agreements of thermoacoustic theory with experiments suggest that thermoacoustic theory of inviscid fluid is useful for accounting regenerator loss and shuttle loss of cryocoolers.