Thermal Systems Research

[IMAGE: Large industrial pipe with multiple sensor attachments running along a concrete wall, with cable trays visible overhead]

Figure 1: Instrumented test section of the primary thermal loop in Building 6. The horizontal pipe run (DN 300) is equipped with thermocouple arrays, pressure transducers, and a clamp-on ultrasonic flow meter. View looking east from the operating gallery.

The Thermal Systems group, led by Prof. Sigrid Lindqvist, conducts research on heat transfer and fluid flow at scales relevant to industrial power systems. The group's primary experimental platform is the Building 6 thermal facility, which provides access to steady-state thermal conditions not achievable in bench-scale laboratory apparatus.

Active Research Areas

Two-Phase Flow Characterisation

Measurements of void fraction, flow regime, and pressure drop in horizontal and inclined large-diameter pipes under steam-water conditions. This work supports the development of improved two-phase flow models for system analysis codes. Recent experiments have focused on the transition from stratified to slug flow in pipes of DN 200 to DN 400. Full project description…

Heat Exchanger Performance Under Extended Operation

Long-duration testing of shell-and-tube heat exchangers to characterise fouling resistance evolution and its impact on overall heat transfer coefficients. The Building 6 primary loop heat exchangers have been instrumented for continuous performance monitoring since 2000. Full project description…

Materials Compatibility in High-Temperature Steam

Exposure testing of candidate structural alloys in flowing steam at temperatures up to 600°C. The programme evaluates oxidation behaviour, embrittlement, and stress corrosion cracking susceptibility. Materials under investigation include Inconel 625, Hastelloy X, and several austenitic stainless steels. Full project description…

Transient Thermal Response of Multi-Loop Systems

Experimental and computational studies of the thermal response of coupled coolant loops under load-following and transient conditions. This work has applications to the design of thermal management systems for facilities requiring high reliability under variable load. Full project description…

[IMAGE: Industrial control room with analog panel instruments, a CRT monitor displaying process graphics, and an alarm annunciator panel on the wall]

Figure 2: Control room of Building 6. The panel desk (left) displays loop temperatures, pressures, and flow rates. The SCADA workstation (right) provides data logging and trend display. The wall-mounted annunciator panel is visible at top centre.

Related Publications

Lindqvist S., Okonkwo M. — "Two-phase flow regime transitions in horizontal large-diameter pipes." Nucl. Eng. Des. 218, 147–158 (2002). [abstract]
Chen R., Lindqvist S. — "Thermal modelling of closed-loop heat transfer systems with multiple parallel loads." Int. J. Heat Mass Transfer 46, 3891–3902 (2003). [abstract]
Lindqvist S. — "Steady-state performance characteristics of electrically heated steam-raising systems." ISOCTA Technical Report TR-2001-08 (internal). [restricted]

Note: ISOCTA Technical Reports are generally restricted to Institute personnel and authorised collaborators. Requests for access should be directed to the Director of Operations.