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Validation: experimental activity is key to enhance the understanding of the systems under investigation

Bespoke tests setup: our lab is equipped with unique test facilities for cryogenic and high temperature applications

Sustainable Cryogenics & Cold Energy Systems

HIGH GRADE COLD ENERGY STORAGE TEST RIG: The test bench principally aims to evaluate the influence of phase change material application (material and geometry) on the efficiency of the cold thermal energy storage systems.  The test bench replicates the charge and discharge phase of a regenerator, namely High-Grade Cold Recycle, to be used in applications such Liquid Air Energy Storage (LAES) and LNG cold energy recovery (from the regasification process).

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An “off the shelf” liquid nitrogen evaporator, with capability of up to -196 °C and 150 bar, is employed. Depending on the heat transfer fluid employed in the regenerator, the test facility includes two separate test benches: i) a SH-PCM (HGCR 1) regenerator test bench; ii) a PCM (HGCR 2) regenerator test bench. The SH-PCM regenerator consists of two sections: in the first one a sensible heat material stores thermal energy within the temperature range from -196 °C to -90 °C while PCM materials are adopted to store thermal energy from -80 °C to 20 °C. Gaseous nitrogen will be used for a twofold purpose: causing liquid nitrogen evaporation at EVA and acting as the heat transfer fluid for regenerator charge/ discharge. It will be transported to evaporator and regenerator by means a secondary circuit composed by a small blower that imposes a variable volumetric flow between 93-327 m3/h  and  air heaters to control the temperature of gaseous nitrogen entering the evaporator (25÷40 °C) in charge mode and the SH-PCM regenerator (-180÷-100 °C) in discharge mode. The PCM regenerator makes use of cold thermal energy released by discharge phase of SH-PCM regenerator at a controlled temperature of approximately -115 °C by means of a cold recuperator heat exchanger (COLD REC):  gaseous nitrogen flows in the interior while the heat transfer fluid in the shell. The latter fluid, a diathermic oil commercially employed for cryogenic application, is collected after the respective regenerator charge and discharge modes in two storage tanks (cold and warm tank). The measurement devices will consist of sensible thermocouples to record the temperatures of the fluids at different parts of the evaporator and regenerator at different moments during the transients. This rig can also serve in the future for other more in-depth projects where cryogenic liquid turbine and other innovative components for LAES can be further studied.

Materials characterization and formulation: to see our equipment please click here. 

Advanced Heat Energy Systems

HIGH TEMPERATURE TEST RIG: The high temperature test bench aims to evaluate the impact of the application of Phase Change Materials (PCM) in steam boilers affected by temperature fluctuations. The main purpose of the test bench is to replicate the temperature fluctuations occurring in the combustion chamber of a Waste-to-Energy (WtE) plant, which affect the performance of its heat recovery system (i.e. steam generator and turbine). Such a temperature fluctuation is reproduced by an electric furnace, which is capable to achieve a maximum temperature of 1,000°C and generate a heating/cooling rate of 15°C/min. The test bench is able to supply 50 kg/h of superheated steam at a maximum temperature of 600°C and at a pressure of 35 bar to the steam heat exchanger installed within the electric furnace. Such a steam heat exchanger replicates the high temperature steam superheater that may be installed in the combustion chamber of a real WtE plant. The PCM-based technology is then mounted on the steam heat exchanger in order to protect it from the temperature fluctuations.

WtE_LabLayout.JPG

ORGANIC RANKINE CYCLE TEST RIG: The ORC test bench purpose is the investigation of the dynamic behaviour of an Organic Rankine Cycle (ORC) evaporator under variable boundary conditions. The system replicates an ORC recovering waste heat from sources with fluctuating thermal power over time, isolating the performance of the evaporator. The system is designed to work with different working fluids: R245fa, R1233zd(E) and Novec649 with evaporator pressures of 4 to 15 bars and mass flow rates of 0.01 to 0.03 kg/s. The hot air is supplied from an electric heater at temperatures of 200 to 400 °C and mass flow rates of 0.08 to 0.3 kg/s at atmospheric pressures.

Before entering the evaporator, the working fluid is pressurized in a pump and its temperature at the inlet of the evaporator is controlled with an electric heater, replicating the conditions after a virtual recuperator. The temperatures and mass flow rates of the working fluid at the outlet of the evaporator are measured. After the evaporator, the working fluid is expanded in an expansion valve after which it condenses in a water cooled condenser and flows back to the storage tank completing the cycle. The expansion valve is controlled as to replicate the effect of back pressure in the evaporator from the operation of a virtual expander.

The evaporator can be decoupled from the rest of the components and substituted if needed in order to test different technologies of heat exchangers with different geometries. The test rig can also serve in the future for the investigation of the heat transfer characteristics of different organic fluids during evaporation. 

ORC.JPG

LOW-MEDIUM TEMPERATURE TEST RIG: The test facility includes two separate test benches: i) thermal electric generator (TEG) test bench, ii) thermal electric module (TEM) test bench. The TEG consist in the reproduction, in scale of the exhaust pipe of a marine engine with a power of 1.5 MW. The equipment consist in a blower, a heater, a pipe and a control system which monitor temperatures, mass flow and electric output. The system will be able to create a mass flow of about 0.5 kg/s of hot air at a temperature of 380 C. The air will flow through the pipe where the TEG generator will be installed. Voltage and current output will be measured with the control system. The hot air will then flow away in the atmosphere. The second, is a small platform to test the behaviour of single TEMs. A steel made frame will support the hot plate and the cold plate in order to create a temperature difference (about 300 C) at the boundaries of the TEM. The system will monitor thermal properties (temperature) as well as electrical ones (Voltage, current).

TEG test rig.JPG

CONTACT US

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THERMAL ENERGY SYSTEMS LAB

School of Mechanical and Aerospace Engineering 

Nanyang Technological University 

Materials Lab 1 / Block N3.1 - B2b - 02

50 Nanyang Avenue, 639798 Singapore

 

For enquiries please contact:

Asst. Prof. Alessandro Romagnoli 

email: a.romagnoli@ntu.edu.sg

 

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