Alan J Fletcher <[email protected]> wrote: As far as I can tell, isoperibolic (I haven't found a formal definition of > the term yet -- what the heck IS a peribole?) calorimetry assumes that the > entire system being tested is fully enclosed in the calorimeter. >
It is often called isoperobol calorimetry. Quoting Hemminger and Hohne, p. 82 and 83: "5.1. Isothermal operation In isothermal operation, the surroundings and the measuring system have the same constant temperature . . . 5.2 Isoperibol Operation The term "isoperibol" operation refers to the use of a calorimeter at constant temperature surroundings with a possibly different temperature of the measuring system. The thermal resistance Rth between the measuring system and the surroundings is infinitesimally small in isothermal calorimeters, a finite magnitude in isoperibolic calorimeters and infinitely large in adiabatic ones . . . FOOTNOTE The term "isoperibol" (uniform surroundings) was introduced by Kubaschweski and Hultgren (1962)" In this case, the constant temperature bath is the room air. The air surrounding the reactor vessel is what fully encloses it. This only works when the air temperature is regulated with precision thermostats. You have to watch out for things like moving currents of air and fans. Mizuno puts his cells into an air "incubator" which is a large box with many fans driving air around inside it at a constant temperature regulated with a precision thermostat. It is like a constant temperature water bath with a stirrer. > How do you ensure that the SINGLE internal/external thermometers (on the > walls of the kernel) are representative of the temperatures as a whole? > (See my two-heating-resistor fake) > I strongly recommend multiple thermocouples, both inside and outside. I also recommend an IR camera in this case to be sure the outer wall temperature is reasonably uniform without hotspots. The configuration with side-by-side reactors, with one active and one as a control, is good. There is a lot to be said for it. But you have to be sure the two reactors have similar heat transfer coefficients. You establish this by calibrating them. Calibration is the key to this method. - Jed
