A Fast-Response Calorimeter with Dynamic Corrections for Transient Heat Transfer Measurements

Abstract

Robust fast-response transient calorimeters with novel calorimeter elements have attracted the attention of researchers as new synthetic materials have been developed. This sensor uses diamonds as the calorimeter element, and a platinum film resistance is sputtered on the back to measure the temperature. The surface heat flux is obtained based on the calorimetric principle. The sensor has the advantages of high sensitivity and not being prone to erosion. However, non-ideal conditions, such as heat dissipation from the calorimeter element to the surroundings, can lead to measurement deviation and result in challenges for sensor miniaturization. In this study, a novel transient calorimeter (NTC) with two different sizes was developed using air or epoxy as the back-filling material. Numerical simulations were conducted to explain the complex heat exchange between the calorimeter element and its surroundings, which showed that it deviated from the assumption of an ideal calorimeter sensor. Accordingly, a dynamic correction method was proposed to compensate for the energy loss from the backside of the calorimeter element. The numerical results showed that the dynamic correction method significantly improved the measurement deviation, and the relative error was within 2.3% if the test time was smaller than 12 ms in the simulated cases. Detonation shock tunnel experiments confirmed the results of the dynamic correction method and demonstrated a practical method to obtain the dynamic correction coefficient. The accuracy and feasibility of the dynamic correction method were verified in a single detonation shock tunnel and under shock tube conditions. The NTC calorimeter exhibited good repeatability in all experiments.

Comparative analysis of the sensitivity of nanometallic thin film thermometers

“…This can be traced to its stability, regard for its ability to provide high measurement accuracy (Cai et al 2012), and well defined TCR (Bernhardsgru et al 2021). Thin Pt films have been applied in high-sensitivity thermal transport measurements (Kim et al 2001, Shi et al 2003, Weathers et al 2013, and into the present, it continues to be the most ubiquitous material used in techniques reliant upon resistance thermometry (Cai et al 2012, Zhang et al 2020, Bernhardsgru et al 2021, Siroka et al 2021, Wang et al 2022.…”