Ajeet Singh
Penrhyn Castle is a National Trust in Bangor, North Wales. The place is historically and archeologically a well-known tourist hotspot. Penrhyn attracts around more than 100,000 visitors annually, where 30% visitors are on a day trip and 70% during holiday [1].
Fig. 1. Penrhyn Castle views (Photos by Paul Coughlan).
A pilot heat recovery system was installed by Dwr Uisce in 2019 for a real time assessment of the thermal recovery potential from wastewater of the commercial kitchen, located in the café’ of Penrhyn Castle. Figure 2 illustrates the pilot thermal recovery system to recapture heat from the high temperature kitchen wastewater. The system has four key components namely two heat exchangers (HX) retrofitted to the drainpipe, a buffer tank (BT), and a heating interface unit (HIU) as shown in part 2b. The fresh cold water from the supply lines goes into the HX gains heat from the kitchen wastewater coming down into the vertical drainpipe. The preheated water from the HX accumulates in the BT. Based on the desired flow rate requirement at the hot water tap end for users, the quantity of preheated water goes in to the HIU. The HIU is coupled with a biomass boiler unit which act as an auxiliary heat source to further increase the temperature of the preheated water to a desired temperature level. The flow through the entire circuit has been achieved using water pumps and addition of heat to the preheated water in the HIU via mixing valve.
Fig. 2. Thermal recovery pilot setup installation for kitchen wastewater heat recovery: (a) a view of the installation site; (b) schematic of various components of the system for better insight.
Fig. 3. Temperature (in degrees Celsius) of the water accumulated inside the buffer tank.
Due to COVID-19, the monitoring was intermittently restricted in the year 2020-2021. In a recent visit, some members of our team visited the pilot site to perform some routine checks and found that the system had been recovering heat for 4 months from the mid-July to the first week of November 2021 (Figure 3). The plot in the figure shows the temperature of the preheated water, demonstrating a significant amount of thermal recovery from the high temperature kitchen wastewater. as per data archived.
With the Castle and café open to visitors again, our research investigation can proceed further. More updates on the ongoing monitoring will be posted on our website and social channels.