ICEBAT UW Internal melting ice storage
Performance and simplicity for air conditioning and refrigeration
In many buildings (shopping centres, commercial and administrative complexes, hospitals, industrial companies, cinemas, theatres, etc.), the need for cooling varies greatly depending on the time of day. During the night, the need for cooling is very low or even non-existent, and it becomes very high during the day.
Refrigeration or cooling installations must be dimensioned to meet peak consumption levels. Thus, their operating rate remains minimal for several hours a day.
In conjunction with a FAFCO ice storage tank, each refrigeration system is designed to maximise efficiency: the refrigeration machine charges the ice storage tank at night when electricity is cheap and the stored cold is fed back into the circuit during the day as required. The economic advantages of this system are therefore considerable.
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The ICEBAT UW is generally very well positioned on air-conditioning plants of more than 100 kW cold. But we have succeeded in demonstrating the versatility of this technology by delivering 32 MWh of cold storage for the Lyon urban cooling network. With Dalkia, we designed a competitive and efficient cooling plant by securing the cold supply using our most standard storage solution, to which we simply added our HP (High Power) module to cover the network’s peak needs.
The glycoled water loop ensures charging and discharging
The standard ICEBAT is both simple in its design and in its use, making its field of application very wide and simplifying its integration into cold production installations.
In order to form the ice inside the ICEBAT, a loop of glycoled water is cooled to -4°C by a cooling unit circulating through a network of Fafco exchangers immersed in the water of the tank. The glycol water will gradually give up its frigories to the water until the water reaches 0°C.
From this point on, a layer of ice will form on the surface of the submerged 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 frozen and the load 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 the mechanical stresses.
This animation represents 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). Ice (white) gradually forms around the tubes. When the neighbouring ice rings meet, they melt until they form a single homogeneous block of ice.
To melt the ice and recover stored frigories, the same glycol water loop is used. Upstream of the ICEBAT, it passes through a plate heat exchanger through which it gives off its frigories. It then enters the accumulator and crosses the exchanger network trapped in the ice. In this way, it will recover the frigories by melting the ice from the inside.
This animation shows the melting of the ice around the tubes of the FAFCO heat exchangers. The glycol water (in green) recovers the cold stored in the ice (in white) through the polypropylene tubes (in black). The ice then gradually melts around the tubes until only water (blue) remains in the accumulator.
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 discharge.
For certain applications, requiring high power available at the end of the load, we offer an optional compressed air stirring system installed under the heat 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 heat exchanger tubes.
This improves heat exchange and ensures maximum discharge power at all times during the discharge.
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