Parameters affecting the accuracy of temperature measurements during high hydrostatic pressure processing

Theoretical analysis of the temperature response of a thermocouple assembly during high hydrostatic pressure processing (HHPP) was carried out to estimate the lag in the temperature measurement. The analysis was carried out for temperature variation during the pressurization, pressure hold and pressure release steps of HHPP. The estimated temperature lag was used to quantify the temperature discrepancy between the measured and the actual temperatures. The solution obtained showed that there could be a lag of approximately 2 K depending on the design of the temperature-measuring device. Equations governing the thermocouple response were nondimensionalized to obtain the parameters that govern the lag in temperature during the HHPP. PRACTICAL APPLICATIONS The results obtained from the theoretical analysis presented are relevant and important in evaluating a high-pressure, high-temperature process. In particular, the method presented allows estimation of inaccuracies of temperature measurement in a high-pressure vessel and its impact on the thermal process calculations (F value).