Development of DexTherm


Neil’s chance opportunity had led to the possibility of rolling out the product to the entire restaurant chain, so he knew his prototype needed to be thoroughly tested, independently quantified and validated.

He was faced with a significant challenge; he needed somewhere with the capability, technical understanding and equipment to put his prototype through its paces and accurately analyse the results.

Neil was also conscious that his idea needed to be protected, so he travelled to Leeds library where there was a service for researching patents. While carrying out this task he talked to a member of staff about his frustration in trying to find a testing facility, and (as so often happens with Neil!) he was talking to the right person at the right time. She recommended a research network where people could submit ‘callouts’ or problems that need to be solved, and academic institutions would bid for the work.

ANSYS Flow Optimisation Study

Neil submitted an application which led to a connection with Hallam Energy – newly established at Sheffield Hallam University by Dr Andy Young.

The DexTherm product was developed and refined by Neil Bracewell in collaboration with Hallam Energy. 

Hallam Energy said: “The heat recovery system had to deliver high performance in a challenging environment, working to recover low-grade waste heat and reintroduce it to the system while overcoming real-world problems like grease fouling and flame protection. Using state-of-the-art modelling techniques including CFD (computational fluid dynamics), a series of experimental runs and analytical engineering methods, we helped DEXT to develop a heat recovery plate that can be installed close to the main heat source within the kitchen, either directly behind a chargrill or cooker, or within a canopy.

Forward-looking Infrared (FLIR) image of the DexTherm image at Nando’s

“The heat is absorbed by the plate and transferred into a sealed water circuit, which is circulated through a coil in a cylinder for hot water generation, providing substantial energy savings for the end user.

“As well as showing very good performance under difficult operating conditions, these systems are effective, robust, relatively low cost and easy to clean.

“After the initial trials, the system is being installed at a number of restaurant chains, including Nando’s and Frankie and Benny’s.”

You can read more of what Hallam Energy said about the project here.

The computational techniques developed during this period would become the baseline for all subsequent research and development.