ICEBAT XM external melting ice
To produce chilled water close to 0°CC
The Fafco external melting ice accumulators (types XM) complete our offer for ice storage. These accumulators provide high performance during discharge by extracting the water from the tank directly from the melting ice. The heat transfer fluid used to charge the accumulator is a mixture of water and glycol.
In addition, the temperature of the water extracted during melting is very low (between 0.5 and 2°C) but is necessarily above 0°C. This represents a major interest for industrial applications, particularly in the food and pharmaceutical industries.
External melting therefore offers independent charging and discharging circuits, which opens up new possibilities, such as charging and discharging the accumulator at the same time, using our storage as a heat exchanger.
Send download link to:
A circuit for charging, a circuit for discharging
The ICEBAT XM takes the design of the standard ICEBAT but adds an inlet and outlet for chilled water. This system makes ice storage solutions compatible with other applications.
In order to form the ice inside the ICEBAT, a loop of glycol water cooled to -4°C by a cooling unit circulates through a network of Fafco exchangers immersed in the water in the tank. The glycol water will gradually give up its frigories to the water until the latter reaches 0°C.
From then on, a layer of ice will form on the surface of the submerged heat exchangers and grow as long as the cooling unit is running.
After 6 to 8 hours, the network of tubes forming the exchangers is completely iced up, and the charging can stop.
In order to preserve the structure of the tank from the expansion of the ice, part of the initial volume of water remains in a liquid state and absorbs mechanical stresses.
This animation shows the formation of ice around the tubes of the FAFCO exchangers. The glycol water (in green) cools the accumulator water (in blue) through the polypropylene tubes (in black). The ice (white) gradually forms around the tubes. When the neighbouring ice rings meet, they melt until they form a single homogeneous block of ice.
In order to melt the ice and recover the stored energy, the ICEBAT XM no longer uses the glycol water loop, but a chilled water loop. Indeed, around the block of ice formed in the ICEBAT, there is always a volume of liquid water remaining. This water is extracted by a collector in the lower part of the tank and transported to a plate heat exchanger or a process in order to cool it down. The heated water then returns to the ICEBAT where it will be sprayed on the block of ice inside the ICEBAT in order to melt it gradually.
This animation depicts the melting of the ice due to the flow of water around the block of ice. The glycol water (green) does not circulate during the discharge. The ice then gradually melts, from the periphery of the ice blog to its center, until only water (in blue) remains in the accumulator.
As the ICEBAT XM is clearly intended for applications requiring a fast discharge or a very low flow temperature, our High Power system is installed by default..
During discharge, the ice gradually melts, first near the tubes and then further and further away. Thus, the heat exchanges at the beginning of the discharge are better than at the end of the charge. We therefore install a compressed air distribution network underneath the exchangers.
Air bubbles are thus injected under the ice during discharge. These bubbles will rise to the surface through the block of ice in the spaces created around the exchanger tubes. This improves the heat exchange and ensures maximum discharge power at all times during the discharge.