Thermal Behaviour of the Residential Buildings with Cantilever Beam under Winter Day Boundary Conditions

Abstract

I n this study, the thermal behaviour of residential buildings with cantilever beam under winter boundary conditions was numerically investigated by means of the open-ended structure approach. For this purpose, parametric studies were carried out for various ratios of cantilever beam depth/cantilever beam height d/H and Rayleigh numbers using a computer program for no wind laminar flow conditions. Analyses were conducted for Rayleigh numbers in the range of 103 to 106 . The calculations were carried out for the ratios of d/H, namely 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0. The working fluid was treated as air Pr=0.71 . According to the findings, the mean Nu number along with the outer vertical wall surface L of the residential building, in general, decreases as d/H increases. This decrease in the mean Nu number is evident for Ra≤104 , but it appears to be more pronounced after Ra=105 . To have minimum heat loss from a residential building under winter day boundary conditions, it is suggested that the ratio of d/H should be between 0.2 and 0.5.

Keywords

• Open-ended structure,Extended boundaries,Cantilever beam,Laminar natural convection

References

1. Chan YL, Tien CL. A numerical study of two-dimensional natural convection in square open cavities. Numerical Heat Transfer 8 (1985) 65-80.
2. Vafai K, Ettefagh J. The effect of sharp corners on buoyancy-driven flows with particular emphasis on outer boundaries. International Journal of Heat and Mass Transfer 33 (1990) 2311-2328.
3. Vafai K, Ettefagh J. Thermal and fluid flow instabilities in buoyancy-driven flows in open-ended cavities. International Journal of Heat and Mass Transfer 33 (1990) 2329-2344.
4. Khanafer K, Vafai K, Lightston M. Mixed convection heat transfer in two-dimensional open-ended enclosures. International Journal of Heat and Mass Transfer 45 (2002) 5171-5190.
5. Elsayed MM, Chakroun W. Effects of aperture geometry on heat transfer in tilted partially open cavities. Journal of Heat Transfer 121 (1990) 819-827.
6. Khanafer K, Vafai K. Buoyancy-driven flows and heat transfer in open-ended enclosures: Elimination of the extended boundaries. International Journal of Heat and Mass Transfer 43 (2000) 4087-4100.
7. Khanafer K, Vafai K. Effective boundary conditions for buoyancy-driven flows and heat transfer in fully open- ended two-dimensional enclosures. International Journal of Heat and Mass Transfer 45 (2002) 2527-2538.
8. Prianto E, Depecker P. Characteristic of airflow as the effect of balcony, opening design and internal division on indoor velocity: A case study of traditional dwelling in urban living quarter in tropical humid region, Energy and Building 34 (2002) 401-409.

9. Lai CM, Wang YH. Energy-saving potential of buildings envelope designs in residential houses in Taiwan. Energies 4 (2011) 2061-2076. 19.
10. Chan ALS, Chow TT. Investigation on energy performance and energy payback period of application of balcony for residential apartment in Hong Kong. Energy and Building 42 (2010) 2400-2405.
11. Chand I, Bhargava PK, Krishak NLV. Effect of balconies on ventilation inducing aeromotive force on low-rise buildings. Building and Environment. 33 (1998) 385-396.
12. Namli L., Effects of built-in balcony on thermal performance in residential buildings: A case study. Journal of Building Physics 40(2) (2016) 125-143.
13. Roache PJ. Computational Fluid Dynamics. Hermosa, Albuquerque, NM, 1982.
14. Young D. Iterative methods for solving partial differential equations of elliptical type. Transactions of the AMS - American Mathematical Society 76 (1954) 92.A
15. Abu-Mulaweh HI, Armaly BF, Chen TS. Laminar natural convection flow over a vertical forward-facing step. Journal of Thermophysics and Heat Transfer 10 (1996) 517-523.
16. Asan H, Namli L. Laminar natural convection in a pitched roof of triangular cross-section: summer day boundary conditions. Energy and Building 33 (2000) 69-73.
17. Asan H, Namli L. Numerical simulation of buoyant flow in a roof of triangular cross-section under winter day boundary conditions, Energy and Building 33 (2001) 753-757.
18. Penot F. Numerical calculation of two-dimensional natural convection in isothermal open cavities. Numerical Heat Transfer 5 (1982) 421-437.
19. LeQuere O, Humphery JAC, Sherman FS. Numerical calculation of thermally driven two-dimensional unsteady laminar flow in cavities of rectangular cross-section. Numerical Heat Transfer 4 (1981) 249-283.