“…The mass flow rate, in-, and outlet temperature of the HTF are some of the most accessible measurements for LTES heat exchangers and are therefore often reported in experimental studies (e.g., [62, 63, 65, 66, 89, 91, 92, 95-97, 106, 123, 124, 141, 152]). Most authors calculate the efflux of energy (e.g., [62,72,76,77,83,90,92,96,97,106,108,110,117,118,124,126,152]), and some the integrated efflux of energy (e.g., [83,87,92,95,97,100,101,103,117,126,152]).…”