Differential Temperature Sensor Research Articles

Differential temperature sensors method for simultaneous determination of thermal conductivity and diffusivity

An attempt has been made to minimize the sources of error involved in the transient probe method for thermal conductivity determination. Two sensors (thermocouples) are mounted parallel to the needle probe at known distances. This modification makes it a device for simultaneous conductivity and diffusivity determination. Thermal conductivity and diffusivity for glycerine, dune sand and mustard seed are determined by this method. Results obtained are compared with those obtained by a calibrated transient probe for conductivity and by a parallel wire method for diffusivity. Analysis of the results prove it to be a better instrument over the traditional ones. The technique can also be used as a direct reading device for conductivity and diffusivity measurements.

HIGHLY ACCURATE PIPE FLOW ENTHALPY DIFFERENCE METER

The pipe flow enthalpy difference meter serves to determine the variation of enthalpy flow rates between two flow cross sections in liquid pipe flows, especially in cases of small temperature differences of the order of about 1 K. Although the flow rate is being measured by an appropriate commercial magnetoinductive flow meter, a precise temperature difference sensor based on the well-known Seebeck effect for thermopiles was designed and constructed for the determination of the bulk temperature difference. Despite the fact that the thermopile consists of 40 thermocouples connected in series, the sensors are located in a pipe cross section of merely 21 mm in diameter, and are fit for application in ionized and slightly corrosive liquids. The output signal of the thermopile amounts to 1.6 m V/K, so that a temperature difference of 1 K can be measured with an accuracy of ±1% (±0.01 K) by means of an appropriate voltage meter under laboratory as well as under field conditions

Design and testing of a microcalorimeter with semiconductor thermopiles as temperature sensor and study of the inclusion of Cu(II) with β-cyclodextri

In this investigation, a microcalorimeter has been designed and tested which is primarily intended for studying heats of reaction in dilute solution at room temperature to 40° C. This microcalorimeter uses semiconductor thermopiles as the temperature difference sensor. Electrical calibration experiments and property testings indicate that the precision of the microcalorimeter is 0.3% for heat changes of about 2 J. The sensitivity is 170 μV mW −1; the time constant is 260 sec. The enthalpy of neutralization of TRIS with standard HCl solution has been measured. At 25°C, Δ H = −47.48±0.16 kJ mol −1, at 30°C, Δ H = −47.08 ± 0.26 kJ mol −1: these results are in good agreement with values given in the literature. Using this microcalorimeter the enthalpy of the inclusion reaction of β-cyclodextrin with Cu(II) in dilute solution was measured and a value of Δ H = −184.2 ± 0.7 kJ mol −1 obtained at 30.0°C.

The seebeck effect in silicon ICs

The Seebeck effect in silicon is investigated to evaluate its usefulness for an integrated temperature difference sensor. The theory of the Seebeck effect is briefly explained and some details of the integrated thermopile, the device exploiting the Seebeck effect, are discussed. The experimental results of the measurements are presented, and the maximum attainable sensitivity, which appears to be of the order of 5 to 50 mV/K for thermopiles with internal resistances of 2 kΩ to 200 kΩ, is calculated. It is concluded that the absence of offset, the high sensitivity and the wide operational temperature range make the thermopile a very valuable transducer.

Application of thin-film DTA to amorphous selenium layers

A system of evaporated thin-film Ag-Bi thermocouples was used as a differential temperature sensor for DTA measurements. The crystallization of thin amorphous selenium layers was observed by means of this method. The presented method may be useful in studying the thermal transformations of thin films that have different compositions and various applications.

13] Microcalorimeters for biological chemistry: Applications, instrumentation and experimental design

This chapter provides an overview for (1) establishing the need for a calorimeter, (2) determining which instrument is best suited to the problem, and (3) setting up a calorimetry laboratory that can operate in the manner necessary to answer thermodynamic and other questions. A calorimeter can measure the quantity of heat associated with a particular process in two distinct ways. The first of these is to measure the temperature rise associated with the heat production. The second method involves the determination of the rate of heat flow resulting from a heat effect. There are two basic procedures to measure this heat flow. The first involves the active use of a Peltier heating-cooling device that is controlled by a feedback system. The second procedure is to use a Peltier device, or other type of differential temperature sensor, in a passive mode. There exist three fundamental types of microcalorimeters. These three types have been designated as batch, flow, and titration calorimeters. The batch calorimeter produces a signal such that the total area under the thermogram is proportional to the heat of the reaction. A flow calorimeter produces a signal that is proportional to the rate of heat production by the reaction. A titration calorimeter is loaded in a manner similar to a batch device with a single concentration of each reagent, but, because addition of the titrant is slow and continuous, the resulting signal is a heat flux.