Pre-design Latent Heat Thermal Energy Storage using Energy from Electricity Grid

Universiti Teknologi Petronas currently uses Gas District Cooling (UTP GDC) as
cooling system in the university. UTP GDC system stores chilled water thermal energy
storage and using electricity generated from gas turbine. The current set up is using huge
volume of tank storage and high capacities of equipments then lead to high operation
cost. Based on previous research, there is still room of improvement for UTP air
conditioning system. In this project, the chilled water thermal energy storage will be
replaced with ice thermal energy storage and the gas turbine as electricity generator will
be replaced with direct electricity from the Tenaga Nasional Berhad grid. The basic
principle of this project is the chillers only run during the off-peak rate to charge the
storage tank for day use. It is to minimize the operating cost. For that purpose, 37100
RTh cooling load needs to be stored. By using ice, the volume of tank storage can be
reduced to 2700m3. Existing tank needs to undergo several modifications to store ice. For
ice storage, it will contain 3 297 700 nodules AC.00. In order to ensure sufficient storage
for the system, 6 brine chillers are used to replace existing 4 electric chillers and 2 steam
absorption chillers. Chillers will be operating for 11 hours during the off-peak rate while
the existing chillers are running 24 hours. The system is going to use four pumps. Each
pump consists of 210 kW. Heat exchanger capacity is 29700 kW. Economic analysis and
design justifications are done to ensure the feasibility of the project. Based on operation
and maintenance cost analysis, this project can save a lot of money for each month of
operation. The saving is at least about RM 100000 per month and value of energy per
unit volume increases 13 times from the existing design. Other design justifications are
environmental protection and high reliability. All of those justifications prove that this
project is viable to develop.