School of Mechanical & Mining Engineering

The centre has a well-deserved international reputation in the area of power conversion. Highlights of the research outcomes include the following:

  • Better tools to identify Queensland's geothermal heat source
  • CO2 geothermal siphon concept to power future development in Queensland
  • Better power generators for low-temperature geothermal and other renewables
  • Advanced condenser technologies for thermal power plants
  • Metal-foam heat exchangers

Find out past grants and contract research


Heat transfer and advanced cooling system program

Overview

The program of heat transfer and advanced cooling system aims to develop low cost, high efficient air-cooled heat exchanger and natural draft cooling tower technologies for renewable power plants (solar and geothermal), and other processing industry cooling such as coal seam gas processing plants.

The group has the world first-class research facilities of 20 meter high natural draft cooling tower and 1.7x1.7 m^2 cross section wind tunnel located in UQ’s Gatton campus. The world first-class research facilities and the strong CFD modelling skills of the research team have made the group the world leader in dry cooling research.

The group is currently working as part of the Australian Solar Thermal Research Institute (ASTRI) to develop novel dry cooling technologies for supercritical CO2 (sCO2) Brayton cycle solar thermal power plants. We are working with industrial partners (Jord International, MakMax, Arrow Energy Pty Ltd and the Centre for Coal Seam Gas (CCSG)) to use natural draft dry cooling system for coal seam gas processing plants. Recently, we work with CTA International Group Pty Ltd on optimising the design of small-scale vertical axis wind turbines based on our team’s strong skill on CFD modelling and the capability of our wind tunnel testing facility.

 

Research Team

Program Leader

  • Dr Zhiqiang Guan

Research Team

  • Dr Zhiqiang Guan
  • Professor Hal Gurgenci
  • Dr Kamel Hooman
  • Mr Hugh Russell
  • Dr Yuanshen Lu
  • Dr Iman Ashtiani Abdi

  • Mr Xiaoxiao Li (PhD candidate)
  • Ms Fadhilah Shikh Anuar (PhD candidate)
  • Mr Yubiao Sun (PhD candidate)
  • Mr Jianyong Wang (PhD candidate)
  • Mr Navid Dehdashti Akhavan (PhD candidate)
  • Mr Peixin Dong (PhD candidate)
  • Mr Mohammad Monjurul Ehsan (PhD candidate)
  • Mr Yuchen Dai (PhD candidate)
  • Mr Christo Nel (MPhil candidate)
  • Mr Andrew Lock (PhD candidate)

 

Research Foci

Low cost hybrid natural draft dry cooling system for solar thermal power plants

A hybrid, small-scale natural draft cooling tower has been developed with modular steel and polymer design, which has the advantages of reducing construction costs time, and improving capability for isolated deployments. A 20 meter high tower has been built in UQ’s Gatton campus (Fig. Gatton 20m tower). The modelling study (Fig. Modelling results of Gatton tower) and extensive tests have been carried with the tower. The tower will service as the testing base for our newly development technologies:

  • Spray cooling, increasing dry cooling efficiency when ambient air is hot;
  • Windbreak walls, allowing the natural draft tower to achieve consistent performance at any scale even in the presence of crosswinds; and
  • Swirl enhancement, increasing the cooling air mass flow rate by generating swirl motion inside the tower.

Gatton 20m tower

Gatton 20m tower
 

Modelling results of Gatton tower

Modelling results of Gatton tower


Spray cooling optimisation

By introducing a small quantity of water with fine droplet size, the performance of dry cooling tower can be greatly improved when ambient temperature is high. In this study, the nozzle selections and the arrangement of spray nozzles are to be optimised using numerical modelling and experimental tests.

3-D numerical models as shown in Fig. Performance simulation with nozzle locations, simulating the spray evaporation and droplet transport, have been conducted to achieve an optimum spray system.

Full scale experimental tests with optimised system are to be carried in the 20m natural draft cooling tower to validate/modify the spray system design.

Performance simulation with nozzle locations

Performance simulation with nozzle locations


Heat exchangers for supercritical CO2 cooling

Both numerical and experimental studies are to be carried out to investigate the heat transfer and pressure drop characteristic of sCO2 cooled in various tube sizes (15 – 25 mm in diameter).

Reynolds-Averaged Navier-Stokes (RANS) turbulence models are used in the CDF modelling aiming to formulate the empirical Nusselt correlation for air-cooled sCO2 heat exchangers design. Finned tube heat exchanger will be optimised based on the identified heat transfer characteristic of sCO2 cooling.

Streamlines of turbulent sCO2 flows within large horizontal tube

Streamlines of turbulent sCO2 flows within large horizontal tube

Experimental study on the heat transfer and pressure drop characteristics of sCO2 cooling will be conducted in our high pressure loop testing facility located in Pinjarra Hills. The experimental results will also serve to validate the numerical results.


Performance study of sCO2 solar plant by optimising the cooling system

An optimum dry cooling system is to be designed for a supercritical CO2 solar power plant addressing the unique challenges of cooling supercritical CO2 near the critical point. Power plant cycle modelling and cost modelling will be conducted to achieve the lowest electricity cost.


Application of natural draft dry cooling tower in coal seam gas production

We have conducted a feasibility study of using our modular steel and polymer natural draft cooling tower design to replace the fan draft cooling system that is widely used in coal seam gas (CSG) processing plants.

A fan driven cooling system not only requires electrical energy for operation but also require periodic maintenance. The fans are the noise source on site, and companies must comply with strict environmental approval conditions regarding the level of noise emissions. Natural draft cooling system will help the CSG industry to reduce the operating and maintenance cost as well as to eliminate the noise generated by fan.

A preliminary design of the natural draft cooling system for the well heat compressor cooling of CSG industry is shown in Fig. Natural draft cooling for CSG plants based on the 3D CFD simulation results (Fig. CFD modelling result).

Natural draft cooling for CSG plants

Natural draft cooling for CSG plants

CFD modelling result

CFD modelling result


Optimisation of vertical axis wind turbines as an alternative of renewable power in urban environment

Vertical axis wind turbines (Fig. Vertical axis wind turbines), with the advantages of having the capability of catching wind from all directions and are more suited to urban areas due to its low noise, have great potential as an alternative of renewable power in urban environment.

We cooperate with the CTA International Group Pty Ltd on optimising the design of small-scale vertical axis wind turbines. Turbine blades will be optimised by CFD modelling. The optimised blade design will be tested in the wind tunnel to verify the performance of the turbines.

Vertical axis wind turbines

Vertical axis wind turbines


Investigation and optimisation of ground source heat pump performance

A ground source heat pump (GSHP) is a heat pump system that utilizes the ground as a thermal energy reservoir. Due to the nearly-constant temperatures of the ground at depths below certain metres, GSHPs can achieve energy efficiencies or coefficients of performance (COPs) substantially better than conventional air-source air conditioning systems.

We are currently doing studies based on Gatton GSHP facility to investigate and improve the thermal dynamics and energy efficiency of ground source heat pump system with strong supports from GSHP industry.


Optimising porous media for thermal applications

Metal foams have been used in many industries such as biomedical, automotive, aerospace, railway, power generation and many others. Generally, the metal foams can be divided into two categories;

  • Closed structure
  • Open-cell structure

The open-cell metal foam can be considered as one kind of porous media that suitable for a superior heat exchanger. It has been studied under the various operating condition, to match numerous heat exchanger applications such as geothermal power plant, fuel cell, exhaust gas recirculation (EGR) cooler, micro-channels and others.

Principally, the open-cell metal foam could enhance the conduction and convection processes due to its highly conductive material (metallic foam) and porous structure. The foam structures are made of inter-connected cells e.g. dodecahedron, which allows fluids to flow through. The complicated foam structure causes a high thermal performance, but also inducing massive pressure drops. Until today, the fundamental of fluid mechanics for this kind of porous media and optimization studies are required to increase the databank of metal foam heat exchanger.

Aluminium open-cell metal foam

Aluminium open-cell metal foam

3D printing foam

3D printing foam

Our projects involve flow visualization studies using laser-diagnostics equipment such as Particle Image Velocimetry (PIV) and Laser-Doppler Anemometry (LDA) in a small blower wind tunnel with 100 by 100 mm cross section, and a large suction wind tunnel with 500 by 500 mm cross section. The aims are to investigate the fluid flow behaviors of porous media, its thermo-hydraulic properties, as well as optimizing the porous media performances. Different types of foam, operating condition and configurations are used in our projects. In the flow visualization experiments, the PIV and LDA systems are used to obtain instantaneous velocity measurements and related properties in fluids. Specifically, the PIV is for the whole-field measurements, while the LDA is a single point measurement technique.

To gain the fluid velocity information, seeding particles are injected into the flow, with the assumption that the seeding particles are able to accurately follow the fluid motion. The velocity of seeding particles will represent the fluid velocity in that measurement area. The PIV and LDA systems use lasers as the source of light, which are double-pulsed laser and continuous laser, respectively. The PIV system includes CCD (Charged-couple camera) cameras the capture the illuminated particles, and the images could be analyzed using an advanced software, DynamicStudio. This software is helpful in setting up the system, acquisition process, as well as images pre-and post-processing. Meanwhile, the LDA system consists of FlowExplorer Unit, Burst Spectrum Analyzer (BSA) Signal and window software package (BSA Flow explorer). This system uses a Doppler shift concept, where the frequency of the scattered light from the seeding particles is shifted by an amount proportional to the particle velocity. The fluid velocity is obtained based on the frequency shift.

3D printing foam

PIV experiments: CCD cameras, Synchronization cables that auto-detected cameras and laser using DantecStudio software and Nd:YAG laser (400 mJ with 532 nm per pulse)

BSA Flow software

BSA Flow software

Flow field of 3D foam

Flow field of 3D foam

Streamlines and flow field

Streamlines and flow field

BSA Flow software: On-line histogram, Flow field of 3D foam Streamlines and flow field

The experiments are conducted in our laser-diagnostic laboratory, which located at Mansergh Shaw Building, The University of Queensland (St. Lucia Campus). The laboratory is also equipped with many other high-technology devices such as a 3D printer, stereo-microscope, hot-wire anemometry, including various handling-equipment for material surface roughness, pressure and temperature measurements.

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