GB1429365A - Calorimeter - Google Patents

Abstract

1429365 Automatic control of temperature NETHERLANDS APPLIED SCIENTIFIC RESEARCH FOR STATE DEFENCE 1 Aug 1973 [2 Aug 1972] 36603/73 Heading G3R [Also in Division G1] The heat absorbed or emitted by a sample 3 at a given temperature in an endothermic or exothermic reaction is determined by a calorimeter comprising a heat flowmeter 4 on which the sample 3 rests in a cavity 2 defined by housing 1, a heat insulating layer 7 surrounding the housing which is itself surrounded by a heater 6, and means arranged automatically to control the heater 6 in response to the temperature difference between the inner and outer surfaces of the layer 7 to minimize the flow of heat therethrough. As described, the housing 1 may be enclosed in a series of insulating layers 7, 9, 11 having lids 7a, 9a, 1 1a, the layers being separated by electric heater jackets 6, 8, which are connected in series and independent of a jacket 5 which determines the temperature of the cavity being supplied by a stabilized voltage supply 17. Jackets 6, 8 are actuated when sensors 12, 13 detect a temperature drop across layer 7. After initial calibration using a sample of known heat capacity, the heat flow through meter 4, which may be a Peltier effect meter, due to a sample 3 may be plotted on a recorder 18 for later analysis. The current through jackets 6, 8 may be determined by a variable transformer 15 driven by a motor 16 controlled by a controller 14, probes 12, 13 being connected in an input resistance bridge thereof.