Contact

Dr. Sebastian Unger

s.ungerAthzdr.de
Phone: +49 351 260 3225

Prof. Dr.-Ing. Dr. h. c. Uwe Hampel

Head
Experimental Thermal Fluid Dynamics
u.hampel@hzdr.de
Phone: +49 351 260 2772

Condensation heat exchanger for passive cooling systems

Background

The storage of spent fuel elements in actively cooled water pools, e.g. by pumps, is common practice in nuclear power plants. A promising approach to enhance the reliability of power plants is a two-phase, passive heat transfer system. Since this concept works without active components like pumps, water pools can be cooled even in beyond-design-basis accidents, e.g. station black out. In such systems a primary heat exchanger is located in the water pool and a coolant evaporates on the inside. By buoyancy the steam flows through a piping system to a secondary heat exchanger located in ambient air. At the secondary heat exchanger the coolant steam get condensed and flows back to the primary heat exchanger by gravitational force.



The heat transfer performance of such a system depends, among others, on the performance of the components. For that reason the reduction of the single heat transfer resistance improves the overall system.

Objective

The project focuses on optimization of the secondary heat exchanger located in the infinity heat sink air. A substantial part of the overall thermal resistance occurs by convective air side heat transfer. Cooling by natural convection was characterized and optimized by numerical methods. Based on this analysis an innovative tube-fin-design was developed and studied under application-oriented experiments in a flow channel.

Results

A preliminary design of an oval finned tube heat exchanger under natural convection was done by CFD-Simulations. Thereby the temperature of the finned tubes was varied to represent different water pool conditions. Furthermore geometrical parameters were modified to optimize the thermal performance.



On the basis of these results a new tube-fin-design was developed and experimental investigated in a flow channel. At different positions along the heat exchanger the temperature was measured by thermocouples to describe the heat transfer of the new fin design. Temperature- and flow velocity distribution was measured in the wake flow region of the finned tube by an anemometric sensor. The experiments on the new fin-tube-design show a higher heat transfer performance of 10 % to 30 % compare to the conventional design.



Logo Areva

Funding

AREVA


Publications

  • Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

    Air-side heat transfer and flow characteristics of additively manufactured finned tubes in staggered arrangement

    International Journal of Thermal Sciences 161, 106752. DOI: 10.1016/j.ijthermalsci.2020.106752 (2020)

  • Unger, S.; Beyer, M.; Pietruske, H.; Szalinski, L.; Hampel, U.

    Natural convection heat transfer performance of additively manufactured tube bundle heat exchangers with novel fin design

    Journal of Heat and Mass Transfer 57, 1193-1203. DOI: 10.1007/s00231-020-03014-5 (2020)

  • Unger, S.; Beyer, M.; Szalinski, L.; Hampel, U.

    Thermal and flow performance of tilted oval tubes with novel fin designs

    International Journal of Heat and Mass Transfer 153, 119621. DOI: 10.1016/j.ijheatmasstransfer.2020.119621 (2020)

  • Unger, S.; Arlit, M.; Beyer, M.; Hampel, U.

    Experimental study on the heat flux of a heat exchanger for passive cooling of spent fuel pools by temperature anemometry grid sensor

    Nuclear Engineering and Design 379, 111237. DOI: 10.1016/j.nucengdes.2021.111237 (2020)

  • Unger, S.; Krepper, E.; Beyer, M.; Hampel, U.

    Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air

    Nuclear Engineering and Design 361, 110549. DOI: 10.1016/j.nucengdes.2020.110549 (2020)

  • Unger, S.; Beyer, M.; Gruber, S.; Willner, R.; Hampel, U.

    Experimental study on the air-side thermal-flow performance of additively manufactured heat exchangers with novel fin designs

    International Journal of Thermal Sciences 146, 106074. DOI: 10.1016/j.ijthermalsci.2019.106074 (2019)

  • Unger, S.; Beyer, M.; Thiele, J.; Hampel, U.

    Experimental study of the natural convection heat transfer performance for finned oval tubes at different tube tilt angles

    Experimental Thermal and Fluid Science 105, 100-108. DOI: 10.1016/j.expthermflusci.2019.03.016 (2019)

  • Unger, S.; Beyer, M.; Arlit, M.; Stasch, P.; Hampel, U.

    An experimental investigation on the air-side heat transfer and flow resistance of finned short oval tubes at different tube tilt angles

    International Journal of Thermal Sciences 140, 225-237. DOI: 10.1016/j.ijthermalsci.2019.02.045 (2019)

  • Unger, S.; Krepper, E.; Hampel, U.

    Numerical analysis of heat exchanger designs for passive spent fuel pool cooling to ambient air

    Nuclear Engineering and Design 333, 224-234. DOI: 10.1016/j.nucengdes.2018.04.011 (2019)


Contact

Dr. Sebastian Unger

s.ungerAthzdr.de
Phone: +49 351 260 3225

Prof. Dr.-Ing. Dr. h. c. Uwe Hampel

Head
Experimental Thermal Fluid Dynamics
u.hampel@hzdr.de
Phone: +49 351 260 2772