Thermal storage tank optimisation

Around 40% of a commercial building’s energy usage results from Heating, Ventilation and Air Conditioning (HVAC) [1]. For commercial landlords, the figure is even bigger, with HVAC accounting for around 70% of the base load (i.e. energy usage discounting tenants’ computers, hardware etc.). With numbers like these, energy efficient cooling can make a big difference to ongoing operational costs, and also provide an environmentally responsible facility.

Figure 1: Predicted thermal distibution with the storage tank during extreme weather condtions.

Synergetics modelled and optimized a thermal storage tank using CFD. The tank was designed to shift the cooling electrical demands from high cost peak electricity to cheaper off peak loads. The clients focus was to run a chiller overnight and store the cold water in a large tank. The stored water could then be used to cool building air flows during the day. A storage tank like this will inevitably incur some losses, but good design optimisation can minimise this, and improve chiller efficiency by running the chiller during cooler night time hours. The optimal solution involved balancing the desire to minimise internal mixing which creates strong thermal gradients within the tank, with finding a design that leads to easy maintenance. This configuration allows the client to run chillers overnight, with minimal storage losses, significantly reducing electrical bills, whilst still providing a comfortable workplace.

 

For further examples of CFD for buildings see our sector page.

[1] Guide to Best Practice Maintenance & Operation of HVAC Systems for Energy Efficiency, AIRAH, January 2012