A laboratory differential scanning calorimeter for measuring heat capacity of liquids

Abstract

A laboratory differential calorimeter was designed and manufactured, this intended to measure the temperature dependence of specific heat capacity of liquid media, including liquids with dispersed solid inclusions, in the temperature range from 20 °C to 100 °C at normal atmospheric pressure.  The device consists of a measuring cell with a sample and a reference liquid of 0.6 ml each, placed in a 2-liter air thermostat with forced air circulation. Control of the air thermostat heater, measurement, and recording of the current temperature values (thermogram) were realized by a multichannel programmable controller and recorder “Termodat-25E6”. Temperature was measured by four copper-constantan thermocouples. The accumulation of initial data (thermograms of test and reference samples) is carried out by the controller automatically, according to the preprogrammed algorithm. The measurements and performance errors of the calorimeter were evaluated in test experiments on measuring the heat capacity of glycerol and two samples of magnetic liquid of the type “magnetite–oleic acid–kerosene” with different volume fractions of the dispersed phase. Oleic acid and chemically pure n-undecane were used as reference liquids respectively. It is shown that measurement errors for liquid media with heat capacity of about 1 kJ/(kg⋅K) do not exceed 10 %.