Minimum Number of Experimental Data for the Thermal Characterization of a Hot Water Storage Tank

Abstract

This paper demonstrates that it is possible to characterize the water temperature profile and its temporal trend in a hot water storage tank during the thermal charge process, using a minimum number of thermocouples (TC), with minor differences compared to experimental data. Four experimental tests (two types of inlet and two water flow rates) were conducted in a 950 L capacity tank. For each experimental test (with 12 TC), four models were developed using a decreasing number of TC (7, 4, 3 and 2, respectively). The results of the estimation of water temperature obtained with each of the four models were compared with those of a fifth model performed with 12 TC. All models were tested for constant inlet temperature. Very acceptable results were achieved (RMSE between 0.2065 °C and 0.8706 °C in models with 3 TC). The models were also useful to estimate the water temperature profile and the evolution of thermocline thickness even with only 3 TC (RMSE between 0.00247 °C and 0.00292 °C). A comparison with a CFD model was carried out to complete the study with very small differences between both approaches when applied to the estimation of the instantaneous temperature profile. The proposed methodology has proven to be very effective in estimating several of the temperature-based indices commonly employed to evaluate thermal stratification in water storage tanks, with only two or three experimental temperature data measurements. It can also be used as a complementary tool to other techniques such as the validation of numerical simulations or in cases where only a few experimental temperature values are available.

Thermal Stratification and Temperature Variation in Horizontal Electric Water Heaters: A Characterisation Platform

“…The timing of the falling slopes in Figure 7 shows that the rate at which the thermocline moves from the bottom to the top at a relatively similar rate between layers 1 and 6 for all longitudinal positions in the tank. This behaviour is also evident in the work done by Castell et al [10], Farooq et al [12], and Gasque et al [27]. However, layer 0, at the top, and layers 7 and 8 at the bottom, show behavioural differences to the analyses and work done for these vertical tanks.…”

“…The latter affects the stratification and temperature variation inside the tank, and therefore has a direct bearing on the balancing act of demand management. As shown above, these have been assessed inside vertically oriented tanks by a multitude of research [10][11][12]15,18,[24][25][26][27]. However, what happens inside horizontal tanks-ubiquitous in developing countries-is currently unknown, meaning results from numerical models of horizontal EWH tanks such as the ones developed in [8,17,19] are largely unvalidated.…”

Comparative Study of Inlet Structure and Obstacle Plate Designs Affecting the Temperature Stratification Characteristics

“…To characterize the temperature distribution in the storage tank, extensive temperature data were acquired during the experiment to validate the numerical model's accuracy. Gasque et al [22] proposed an effective method to minimize the number of measurement points and confirmed this methodology by validating the experimental results with numerical results.…”

Impact of buoyant jet entrainment on the thermocline behavior in a single-medium thermal energy storage tank

“…In terms of experimental measuring techniques, most of the studies installed intrusive temperature sensors within the body of the storage tank to monitor the temperature evolution at several fixed points [35]. However, information on the local velocity profiles, essential for characterizing the jet entrainment phenomenon, cannot be acquired with this method.…”