Feature
Terry February
The ice thermal storage system of the Capitec head office in Stellenbosch has one of the country ’ s largest installations . takes to build up the ice in the tanks . Should only a short time be available , the task would usually be possible , however the equipment setup required would be extensive and may make this solution unsuitable . The longer the period is to build ice storage , the smaller the refrigeration system needs to be .
“ Inclusion of ice storage in a system enables a reduction in all of the components , foremost a saving on the cost of the equipment itself .”
It is recommended in determining system sizing to gather data from a minimum seven-day , 24-hour exercise to establish lowest profile and peak demand . This also indicates specific activity based on the building or facility . For example , certain retailers have very little activity throughout the week but on weekends have a continual load to manage . Similarly , an office building may only need to cater to full occupancy on Mondays and Fridays as during the rest of the week employees are working from home .
As a simple example , taking a peak heat load at 1 000 kW of cooling required , there is a general guideline of 60 / 40 where a 600 kW chiller , that can handle the ‘ normal load ’ is installed . When the chiller runs out of capacity , normal load is being exceeded so it is then supplemented by starting the chiller with a 400kW ice storage system . The chiller then rebuilds the ice overnight and repeats the process during successive off-peak periods .
Various sensors are also available to monitor such things as the thickness of the ice , the variance in the tanks , the proportion of ice to liquid and so on .
WAY FORWARD AND INCENTIVES Many role players agree that thermal storage is a good fit within green building design and implementation . South Africa has a praised Green Building Council , that is very technically sound and up-to-date with all the latest trends and designs , however there are no incentives anymore in this country to push green technology , other than the desire to partake in reducing carbon emissions , and thus global warming . Therefore , it has been noted that only large corporations partake in green initiatives .
“ The world ' s problems can obviously be solved by human ingenuity ; we have it within us . We have the skill and the technology , and we know what the problems are with regards to polluting the planet and global warming . However , you can have this ingenuity in infinite volumes , but if there is no clear desire to reduce your carbon footprint , or an incentive to change , things will always be an uphill battle . Many countries around the world incentivise property owners and developers to implement green technologies and particularly for a country like ours where incentives are required , this will remain a key factor in driving this solution to ultimately support our ongoing energy dilemma ,” concludes van der Merwe .
For further reading about ice thermal storage , please visit the RACA Journal website : http :// www . refrigerationandaircon . co . za where more information about how the various systems work , as well as technical information . RACA
www . hvacronline . co . za RACA Journal I April 2021 17