Heat recovery optimization of a shell and tube bundle heat exchanger with continuous helical baffles for air ventilation systems

• Published in: International Journal of Air-Conditioning and Refrigeration 2024, 32(1), , pp.1-16
• Main Authors: Bari, Md Ashfaqul, Münsch, Manuel, Schöneberger, Bastian, Schlagbauer, Bernhard, Tiu, Andrea Alina, Wierschem, Andreas
• Format: Article
• Language: English
• Subjects: Air temperature; Air to air heat exchanger; Baffles; Compact recuperative heat exchangers; Composite materials; Continuous helical baffle; Convective heat transfer; Counterflow; Cross flow; Cross-counter flow; Decentralized ventilation; Efficiency; Energy conservation; Energy consumption; Energy efficiency; Fluid flow; Geometry; Green buildings; Heat conductivity; Heat exchangers; Heat recovery; Heat recovery systems; Heat transfer; Helical flow; Inclination angle; k-\omega$$ k - ω transition SST; Optimization; Polymers; Pressure loss; Residential energy; Shear stress; Shell and tube; Temperature gradients; Turbulence models; Ventilation; 기계공학
• ISSN: 2010-1325; 2010-1333
• DOI: 10.1007/s44189-023-00046-4

We report a numerical evaluation of the impact of continuous helical baffle on the heat recovery efficiency of counterflow tube bundle heat exchangers. The baffle inclination angle has been varied from 11∘ to 22∘. Since the fluid flows over the tube bundle at an angle due to helical flow inside the shell, the heat exchanger operates in cross counter mode. Fluent simulations with the k-ω transition shear stress transport turbulence model have been performed to investigate the thermal-hydraulic parameters of the system in terms of heat recovery efficiency, pressure loss, and overall heat transfer rate. Outside air temperature has been varied to mimic cold and warm weather. Pressure loss has been constrained to be less than 250 Pa, conforming to EU guidelines for energy labeling of residential ventilation units. At the maximum volume flow rate of 40 m3/h, the device performed with over 80% heat recovery efficiency for the considered temperature difference. Continuous helical baffles helped to improve convective heat transfer by reducing cross flow area and increasing velocity. Smaller angles result in greater pressure loss while having no discernible effect on heat recovery efficiency for the considered geometry. The analysis demonstrates the potential of a compact counterflowing recuperative heat exchanger with continuous helical baffles for decentralized ventilation systems and serves as a basis for further optimization.