Numerical investigation of building integrated solar thermal collectors under diverse conditions

Figures & data

Table 1. Boundary conditions that are considered for the numerical simulation.

Study	Boundary Conditions
	Solar Radiation	Mass Flow Rate	Wind Velocity	Initial Fluid Temperature	Inlet Fluid Temperature	Ambient Temperature
	[W/m^2]	[Kg/s]	[m/s]	[°C]	[°C]	[°C]
Jiandong, Hanzhong, and Susu (2015)	700	0.005	4	–	20	15
Vetter, Fischer, and Dr√(ck (2018)	788	0.042	2	–	19.9–79	22
Gunjo, Mahanta, and Robi (2017)	700	0.0125 & 0.025	–	–	15–45	25
Fertahi et al. (2018)	–	0.26	–	60	95	–
Long et al. (2020)	1000	0.01–0.08	–	20	20	22
Garnier, Muneer, and Currie (2018)	400	0.02	–	–	–	20.5
Wang et al. (2015)	800	0.025 & 0.25	–	–	–	–
Leone and Beccali (2016)	Dynamic	Dynamic	–	–	Dynamic	Dynamic
Rangababu, Kiran Kumar, and Srinivasa Rao (2015)	1030	–	1.4 & 2.25	–	–	21.85–25.85
Ababsa and Bougoul (2017)	–	–	–	–	Dynamic	–
Sami, Marin, and Rivera (2016)	Dynamic	–	–	–	–	–
Quitiaquez et al. (2020)	650 & 800	0.02 & 0.1	–	–	–	–
Andrade Cando, Quitiaquez Sarzosa, and Toapanta (2020)	1200	0.0125	2	–	31.85	36.85
Mintsa Do Ango, Medale, and Abid (2013)	350–1200	0.0025 & 0.005	–	–	20,30,40	–
Medina Carril et al. (2016)	786	–	14	–	–	32
Fowzi (2017)	Dynamic	0.0221	–	–	–	–
Nayak et al. (2018)	950	0.004123	–	–	29.85	35
Agathokleous et al. (2019)	121–440	0.02	–	–	–	24

Table 2. Numerical Simulation model characteristics.

Study	Numerical model characteristics
	Software	Design	Conservation Equations	Location	Collector Type	Collector Dimensions
Jiandong, Hanzhong, and Susu (2015)	–	3D	Mass, Momentum and Energy	Guangzhou, China	Flat Plate	Solar Collector plate thickness: 0.1–2.1 mm
Vetter, Fischer, and Dr√(ck (2018)	Virtcoll + Project	3D	Mass, Momentum and Energy	Wurzburg, Germany	Flat Plate	–
Gunjo, Mahanta, and Robi (2017)	Ansys Fluent	3D	Momentum and Energy	–	Flat Plate / Cooper	Solar Collector length, width: 1.65, 0.1 m Tube diameter, thickness: 0.0125 m,0.007m
Fertahi et al. (2018)	OpenFOAM	3D	Mass, Momentum and Energy	Fez, Mexico	Flat Plate / Cooper	Collector length, external, internal diameter: 1.8 m,58 mm,47mm
Long et al. (2020)	Ansys Fluent	3D	Mass, Momentum and Energy	–	Flat Plate / Cooper	Solar Collector Size: 130 mm x 2 mm x 2000mm
Garnier, Muneer, and Currie (2018)	Ansys Fluent	3D	Momentum and Energy	Edinburgh, UK	Flat Plate	Solar Collector Size: 1400 mm x 700mm
Wang et al. (2015)	Ansys Fluent	3D	Momentum and Energy	Guangzhou, China	Flat Plate	Solar Collector Size: 1960mm x 1000mm
Leone and Beccali (2016)	Comsol	2D & 3D	Convective heat exchange and radiative flux	–	Flat Plate	Solar Collector Length: 2500mm
Rangababu, Kiran Kumar, and Srinivasa Rao (2015)	Ansys Fluent	3D	Useful gain heat	Warangal, India	Flat Plate	Solar Collector Size: 915 mm x 810 mm x 95mm
Ababsa and Bougoul (2017)	Ansys Fluent	3D	Mass, Momentum and Energy	–	Flat Plate	Solar Collector Size: 1360 mm x 680mm
Sami, Marin, and Rivera (2016)	Comsol	3D	Energy and Heat transfer	–	Flat Plate	Solar Collector Size: 1360 mm x 680mm
Quitiaquez et al. (2020)	Ansys Fluent	3D	Mass, Momentum and Energy	–	Flat Plate	Solar Collector length, thickness 960 mm/0.001m
Andrade Cando, Quitiaquez Sarzosa, and Toapanta (2020)	Ansys Fluent	3D	Mass, Momentum and Energy	–	Flat Plate	Solar Collector Size, thickness: 1600 mm x 10 mm /0.001m
Mintsa Do Ango, Medale, and Abid (2013)	Star-CCM	3D	Mass, Momentum and Energy	–	Flat Plate	Module size, thickness: 2000mm x 200 mm/62mm
Medina Carril et al. (2016)	Ansys Fluent	2D	Net heat flow	Merida, Mexico	Flat Plate	–
Fowzi (2017)	Matlab	1D	Mass, Momentum and Energy	–	Flat Plate	Riser Length: 1200mm
Nayak et al. (2018)	Ansys Fluent	3D	Mass, Momentum and Energy	Sultanate of Oman	Flat Plate	Solar Collector size, thickness: 980 mm x 980 mm/10mm
Agathokleous et al. (2019)	Matlab	1D	–	Limassol, Cyprus	Flat Plate	Solar Collector size, thickness: 1631 mm x 846 mm/0.6mm

Figure 1. Water Consumption [L/h] Versus Time [h].

Table 3. Boundary Conditions.

Property	Value	Units
Thermal medium mass flow rate	0.038	[kg/s]
Solar thermal radiation	Transient (Georgiou et al. 2021)	[W/m²]
Ambient Temperature	Transient (Georgiou et al. 2021)	[°C]
Water consumption profile	Transient (Figure 1)	[kg/s]
Water initial temperature	Regulated (24 h initial operation)	[°C]
Inclination	0,45,90	°

Table 4. Investigated Configurations – Domains.

System	Model configuration	Domain Mesh	Mesh Information
Uniform Riser			Size of cells per X: 0.0841 (m) Size of cells per Y: 0.0845 (m) Size of cells per Z: 0.0841 (m) Minimum gap size: 0.0222 (m) Total Cells: 423,235 Fluid Cells: 230,906 Solid Cells: 192,329 Fluid Cells contacting solids: 101,890
Multiple Riser Configuration One			Size of cells per X: 0.0866 (m) Size of cells per Y: 0.0941 (m) Size of cells per Z: 0.0841 (m) Minimum gap size: 0.0222 (m) Total Cells: 707,507 Fluid Cells: 353,310 Solid Cells: 354,197 Fluid Cells contacting solids: 181,007
Multiple Riser Configuration Two			Size of cells per X: 0.0853 (m) Size of cells per Y: 0.0862 (m) Size of cells per Z: 0.0841 (m) Minimum gap size: 0.0222 (m) Total Cells: 655,434 Fluid Cells: 327,807 Solid Cells: 327,627 Fluid Cells contacting solids: 167,792

Table 5. Investigated Configurations – Domains (cont’d).

Riser	Riser Configuration	Fluid Flow Illustration	System Description
Uniform Riser			Uniform riser One inlet One outlet
Multiple Riser Configuration One			Three groups of risers assembly. Each group consists of four individual risers. Each riser has one inlet and one outlet. Fluid flows through the first group, then to the second, then to the third and then back to the tank inlet.
Multiple Riser Configuration Two			Three groups of risers assembly. Each group consists of four individual risers. Three inlets, three outlets Fluid flows simultaneously through all three riser groups and exits towards the tank inlet.

Figure 2. Building-integrated Solar Collector Structure.

Figure 3. Riser Fluid Velocity – Uniform Riser.

Figure 4. Riser Fluid Velocity – Multiple Riser Configuration One.

Figure 5. Riser Fluid Velocity – Multiple Riser Configuration Two.

Table 6. Building-Integrated Solar Collector Materials.

Solar Collector
Component Description	Material	Thermal Conductivity [W/(m·K)]	Heat Capacity [J(Kg·K)]	Density [kg/m^3]	Thickness [cm]	Dimensions [m]
Front case cover	Glass	0.74976	834.61	2457.6	0.20	1.66 [L] x 1[W]
Case	Aluminium	200	900	2700	10.00	1.68 [L] x 1.02 [W]
Riser	Cooper	390	390	8900	0.09	1.6 [L] x 1 [W]
Pipes	Cooper	390	390	8900	0.09	Variable
Pipes Insulation	Polyurethane	0.05	1500	70	2.00	Variable
Tank	Cooper	390	390	8900	0.09	1.16 [L] x 1.34 [Perimeter]
Tank Insulation	Mineral Wool	0.035	837	70	5.00	1.25 [L] x 1.8 [Perimeter]
Case insulation	Mineral Wool	0.035	837	70	5.00	1.57 [L] x 1 [W]
Masonry Wall
Component Description	Material	Thermal Conductivity [W/(m·K)]	Heat Capacity [J(Kg·K)]	Density [kg/m^3]	Thickness [cm]	Dimensions [m]
Exterior	Mortar Plaster	1.000	1000	700	2.50	1.68 [L] x 1.02 [W]
Interior	Mortar Plaster	1.000	1000	700	2.50	1.68 [L] x 1.02 [W]
Brick	Hollow Brick	0.400	900	880	20.00	1.68 [L] x 1.02 [W]
Brick Air Holes	Air	0.025	1008	1.23	20.00	5 × 5

Table 7. Minimum, average and maximum – System fluid temperatures [°C] at Slope 0°.

	Uniform Riser			Multiple Riser Configuration One			Multiple Riser Configuration Two
	Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]
Autumn	21.09	22.37	23.84	24.87	28.88	33.74	23.36	26.22	29.69
Winter	14.72	16.38	18.26	15.60	17.87	20.43	15.60	17.84	20.39
Spring	21.86	25.93	30.72	24.17	29.93	36.78	24.19	29.91	36.73
Summer	35.07	40.15	45.91	37.96	45.47	54.00	38.00	45.46	53.90

Table 8. Minimum, average and maximum – System fluid temperatures [°C] at Slope 45°.

		Uniform Riser			Multiple Riser Configuration One			Multiple Riser Configuration Two
		Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]
Autumn	South	25.59	30.05	35.25	27.97	34.36	42.07	27.99	34.36	41.98
	West	23.08	25.60	28.96	24.52	28.03	32.67	24.51	28.01	32.63
	North	20.67	21.65	22.80	21.09	22.37	23.84	21.08	22.36	23.83
	East	22.79	25.65	28.56	24.04	28.05	32.20	24.05	28.04	32.16
Winter	South	15.80	18.15	20.84	17.10	20.38	24.13	17.09	20.33	24.04
	West	14.59	16.04	17.84	15.42	17.39	19.82	15.41	17.36	19.77
	North	13.53	14.39	15.33	13.94	15.06	16.28	13.93	15.04	16.27
	East	14.50	16.11	17.77	15.25	17.47	19.75	15.26	17.44	19.70
Spring	South	23.00	27.78	33.46	25.71	32.63	40.91	25.75	32.61	40.85
	West	21.30	24.80	29.45	23.42	28.36	34.91	23.40	28.34	34.97
	North	18.17	19.90	21.88	19.08	21.38	24.01	19.09	21.37	23.97
	East	20.89	24.85	28.84	22.80	28.38	34.09	22.81	28.38	34.03
Summer	South	34.46	39.49	45.21	37.19	44.53	52.96	37.25	44.51	52.92
	West	34.33	38.52	44.26	37.03	43.18	51.55	37.03	43.15	51.54
	North	32.48	35.65	39.10	34.48	38.97	43.88	34.49	38.94	43.82
	East	33.62	38.79	43.73	36.02	43.51	50.88	36.01	43.49	50.80

Table 9. Minimum, average and maximum – System fluid temperatures [°C] at Slope 90°.

		Uniform Riser			Multiple Riser Configuration One			Multiple Riser Configuration Two
		Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]	Min [°C]	Average [°C]	Max [°C]
Autumn	South	25.00	28.98	33.61	27.12	32.89	39.74	27.16	32.81	39.50
	West	22.03	23.78	26.22	23.02	25.44	28.80	23.00	25.40	28.71
	North	20.20	20.90	21.71	20.44	21.32	22.32	20.43	21.30	22.29
	East	21.71	23.82	25.78	22.55	25.48	28.23	22.57	25.43	28.14
Winter	South	15.45	17.54	19.91	16.59	19.52	22.84	16.60	19.46	22.71
	West	13.98	15.01	16.33	14.56	15.94	17.68	14.55	15.91	17.63
	North	13.12	13.66	14.24	13.33	14.04	14.79	13.32	14.03	14.77
	East	13.83	15.00	16.12	14.34	15.94	17.46	14.35	15.90	17.40
Spring	South	20.92	24.42	28.52	22.89	27.83	33.67	21.95	26.59	32.21
	West	19.55	21.85	25.16	20.98	24.19	28.77	19.78	22.91	27.37
	North	16.81	17.75	18.80	17.17	18.34	19.66	16.15	17.09	18.28
	East	18.94	21.76	24.21	20.15	24.10	27.57	19.13	22.82	26.13
Summer	South	30.81	34.06	37.67	32.39	36.27	40.70	32.40	36.21	40.58
	West	31.97	35.19	40.18	33.81	37.83	43.86	33.79	37.76	43.63
	North	28.91	30.12	31.37	29.52	30.88	32.30	29.53	30.85	32.25
	East	31.04	35.22	38.98	32.74	37.90	42.58	32.74	37.83	42.42

Figure 6. Experimental Vs Numerical – Riser Outlet – Fluid Temperature.

Figure 7. System Average Fluid Temperature – Multiple Riser Configuration One – Water Consumption Comparison – August – South – Slope 90° – Last 24 h.

Figure 8. System Average Fluid Temperature – Multiple Riser Configuration One – Water Consumption Comparison – November – South – Slope 90° – Last 24 h.

Figure 9. Average System Temperature [°C] – All Months, Slope 0°,45° and 90°.

Figure 10. Average System Temperature [°C] Vs Orientation – All Months, Slope 45°.

Figure 11. Average System Temperature [°C] Vs Orientation – All Months, Slope 90°.

Figure 12. Total daily Heat flux [W/m²] Inwards and Outwards of the building wall – Building Integrated Solar Collector Vs No Solar Collector.

Figure 13. Temperature distribution [K] Outer surface of the collector end in the area in contact with the building envelope – System 2A – August – South Orientation.

Figure 14. Temperature distribution [K] Outer surface of the collector end in the area in contact with the building envelope – System 2A – March – South Orientation.

Figure 15. Temperature distribution [K] Outer surface of the collector end in the area in contact with the building envelope – System 2A – November – South Orientation.

Figure 16. Temperature distribution [K] Outer surface of the collector end in the area in contact with the building envelope – System 2A – January – South Orientation.

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Data availability statement

The data that support the findings of this study are openly available in Mendeley Data and Zenodo at http://doi.org/10.17632/xcpyjj2gv7.2 and http://doi.org/10.5281/zenodo.5284639 respectively.