www . refrigerationandaircon . co . za RACA Journal I August 2023 27
Feature for later use . By utilising electric power during off-peak hours when energy is abundant and less expensive , thermal storage systems create ice . This stored ice is then melted during peak daytime hours when electric energy demand is high and costly - supplementing the cooling systems of buildings .
To cater to various applications , three ice melt system designs are available :
• Internal melt
• External melt , and
• External melt with air agitation .
Internal melts are suitable for single-building or small-scale applications , providing a 3 ° C supply of glycol . External melts offer a quiet melt process without air agitation and can achieve a 2 ° C to 3 ° C supply of glycol . External melts with air agitation are commonly used in larger systems or district cooling applications . This design can provide a 1 ° C supply of water and utilises power during the night .
Ice storage systems offer an energy-efficient cooling solution that aligns with fiscal responsibility and environmental commitments . By reducing demand on electrical infrastructure , ice storage eases the strain on utilities and decreases the cost of electrical and HVAC system components in buildings . Consequently , this aids utilities in avoiding the construction of new power plants , resulting in reduced carbon emissions .
Analogous to the cooling load in buildings , electric utilities ' demand experiences low points at night and peaks during the afternoon when people are present and energy consumption is high . Implementing ice storage can help flatten the utility ' s demand profile , enhancing its efficiency with existing equipment . For every four buildings equipped with ice storage , utilities can serve five effectively .
SIGNIFICANT COST SAVINGS Beyond environmental benefits , ice storage systems generate substantial cost savings . By minimising the size of equipment components in air conditioning systems , the initial costs of equipment and installation are reduced . Smaller component sizes also result in lower electrical kW requirements , saving on ‘ first cost ’ of electrical distribution , wiring , starters , and transformers . When combined , these mechanical and electrical savings enable the implementation of a lowest-cost chilled water system as you start construction of your building .
Another benefit is a lower operational cost : power at night is much cheaper than during the day and when employed during the day can dramatically reduce the operating cost throughout the life of a building .
The efficiency of an ice air cooled chiller is also much higher because the nighttime ambient delta is at least 10-15 ° C . Chillers work better during the night as the typical utility most efficiently
A mine ’ s thermal storage structure , ultimately buried underground .
A thermal storage structure under construction .
produces power in the middle of the night , which simultaneously translates to lower air emissions ( GHGs ).
Thermal ice storage is recognised for its sustainability by esteemed organisations such as the US Green Building Council , ASHRAE , and the International District Energy Association . The US Green Building Council ' s Leadership in Energy and Environmental Design ( LEED ) rating system grants credits for thermal ice storage in energy and atmosphere categories . ASHRAE ’ s Green Guide recommends thermal energy storage and district energy plants to reduce energy consumption , lower greenhouse gas emissions , and enhance system efficiency . Source : Evapco promotional film on thermal storage .
HISTORY AND BACKGROUND OF THERMAL STORAGE IN THE HVAC INDUSTRY Andre van der Merwe , Evapco managing director , explains that the concept of thermal storage has its roots in the 1930 ’ s dairy farming industry . “ Farmers faced the challenge of cooling large quantities of milk quickly during specific periods while avoiding the installation of oversized refrigeration systems that would remain idle for most of the day . To overcome this , they developed a smaller cooling system that operated during the day to manufacture ice and stored it for later use when the cooling demand peaked .”
www . refrigerationandaircon . co . za RACA Journal I August 2023 27