Measurement and thermal characterization of graywater discharge events for house-central collection systems in the context of heat recovery

ABSTRACT Within this work, a detailed measurement with a temporal resolution of 3 s of flow rate and temperature of a house-central graywater system was carried out. Individual discharge events could be identified and assigned to specific types of use via user surveys and current measurements. Due to the consistent recording of measurement errors, the accuracy of the determined data could be improved. Error rates of approximately 0–30% were determined, depending on the tab. Thus, accurate statements on the existing temperature distribution for the graywater of specific tabs could be determined. Tab-specific temperature distributions were calculated with ranges of 16–50 °C and an overall mean value of approximately 28 °C. Furthermore, a novel data basis could be provided by evaluating the time-related rate of change of temperatures. This enables more precise simulations to be carried out. For some tabs, significant differences to previous assumptions became apparent. The high temporal resolution of the data also enables simulative considerations that go beyond previous longer-scale energy balances.