Abstract
Insufficient fresh air supply due to the increased air tightness of building envelopes after building renovations and window upgrades is a major concern of HVAC engineering today. The paper demonstrates the application of CFD simulations in the development of a compact decentralised ventilation unit with integrated heat recovery system for local ventilation of rooms, targeting this common issue. The device houses an innovative cyclically rotating recuperative heat exchanger, allowing effective condensate removal and de-icing in winter for its independent operation throughout the year. The paper introduces the ventilation unit, describes preparation of its numerical models, and conducts CFD simulation using Ansys Fluent software. The initial design of the device was improved following the findings of the numerical analysis, and the proposed adjustments were tested through follow-up CFD simulations, confirming that the desired outcomes were achieved. A separate CFD analysis was performed to assess the use of different air supply elements at the air outlet to the room, recommending the use of adjustable nozzles. A prototype ventilation unit was manufactured and the volume flow rate under different operating conditions was measured to be compared with the simulation results. The outcome of the research is a new type of compact local ventilation unit. An increase in device energy efficiency was achieved, with the aid of simulations, while maintaining its compact size. In addition to presenting the potential of using variant CFD analysis in the development of new HVAC equipment, the paper also indicates the drawbacks of using the Multiple Reference Frame (MRF) method to approximate the rotation of radial fan impellers in CFD simulations.
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Abbreviations
- k :
-
turbulence kinetic energy (m2/s2)
- n :
-
rotation speed (r/min)
- Δp :
-
pressure difference (Pa)
- \(\dot{V}\) :
-
volume flow rate (m3/s)
- ε :
-
turbulence dissipation rate (m2/s3)
- ρ :
-
density
- CAD:
-
computer-aided design
- CFD:
-
computer fluid dynamics
- DC:
-
decentralised unit
- EHA:
-
exhaust air
- EPP:
-
expanded polypropylene
- HVAC:
-
heating, ventilation, and air-conditioning
- HRV:
-
heat recovery ventilation unit
- HRX:
-
heat recovery exchanger
- IDA:
-
indoor air
- ODA:
-
outdoor air
- SUP:
-
supply air
- UDF:
-
user-defined function
References
Justo Alonso M, Liu P, Mathisen HM, et al. (2015). Review of heat/energy recovery exchangers for use in ZEBs in cold climate countries. Building and Environment, 84: 228–237.
Ansys (2018). Fluent user’s guide. Canonsburg, USA: Ansys Inc.
Bianco N, Fragnito A, Iasiello M, et al. (2023). A CFD multi-objective optimization framework to design a wall-type heat recovery and ventilation unit with phase change material. Applied Energy, 347: 121368.
European Commission (2014a). Commission Regulation (EU) No 1253/2014 of 7 July 2014 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for ventilation units.
European Commission (2014b). Commission Delegated Regulation (EU) No 1254/2014 of 11 July 2014 supplementing Directive 2010/30/EU of the European Parliament and of the Council with regard to energy labelling of residential ventilation units.
Farhat O, Faraj J, Hachem F, et al. (2022). A recent review on waste heat recovery methodologies and applications: Comprehensive review, critical analysis and potential recommendations. Cleaner Engineering and Technology, 6: 100387.
Gao CF, Lee WL (2009). Optimized design of floor-based air-conditioners for residential use. Building and Environment, 44: 2080–2088.
Gullberg P, Löfdahl L, Adelman S, et al. (2009). A correction method for stationary fan CFD MRF models. SAE Technical Papers.
Gullberg P, Sengupta R (2011). Axial Fan Performance Predictions in CFD, Comparison of MRF and Sliding Mesh with Experiments. SAE Technical Paper 2011-01-0652. Warrendale, PA, USA: SAE international.
He Y, Chu Y, Zang H, et al. (2022). Experimental and CFD study of ventilation performance enhanced by roof window and mechanical ventilation system with different design strategies. Building and Environment, 224: 109566.
JCGM (2008). Evaluation of measurement data - Guide to the expression of uncertainty in measurement.
Kim MK, Baldini L (2016). Energy analysis of a decentralized ventilation system compared with centralized ventilation systems in European climates: Based on review of analyses. Energy and Buildings, 111: 424–433.
Kim MK, Liu J, Baldini L (2024). Numerical analysis, design and application of a decentralized ventilation system with a heat recovery unit adapting to Nordic climates: A case study in Norway. Energy Reports, 11: 3863–3875.
Moreau S, Henner M, Brouckaert JF, et al. (2007). Numerical and experimental investigation of rotorstator interaction in automotive engine cooling fan systems. in: Proceeding of the 7th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, Athens, Greece.
Norton T, Sun D, Grant J, et al. (2007). Applications of computational fluid dynamics (CFD) in the modelling and design of ventilation systems in the agricultural industry: A review. Bioresource Technology, 98: 2386–2414.
Pavíiček T (2024). Local ventilation and air conditioning units. PhD Thesis, CTu Prague, Czech Republic.
Pekdogan T, Tokuç A, Ezan MA, et al. (2021). Experimental investigation on heat transfer and air flow behavior of latent heat storage unit in a facade integrated ventilation system. Journal of Energy Storage, 44: 103367.
Ratajczak K, Amanowicz Ł, Szczechowiak E (2020). Assessment of the air streams mixing in wall-type heat recovery units for ventilation of existing and refurbishing buildings toward low energy buildings. Energy and Buildings, 227: 110427.
Shih TH, Liou WW, Shabbir A, et al. (1995). A new k−ϵ eddy viscosity model for high Reynolds number turbulent flows. Computers & Fluids, 24: 227–238.
Silva MF, Maas S, de Souza HA, et al. (2017). Post-occupancy evaluation of residential buildings in Luxembourg with centralized and decentralized ventilation systems, focusing on indoor air quality (IAQ). Assessment by questionnaires and physical measurements. Energy and Buildings, 148: 119–127.
Singh KK, Mahajani SM, Shenoy KT, et al. (2007). CFD modeling of pilot-scale pump-mixer: Single-phase head and power characteristics. Chemical Engineering Science, 62: 1308–1322.
SVS FEM (2024). SVS FEM PorZo ACT extension. Available at https://www.svsfem.cz/act.
Szlivka F, Hetyei C, Fekete G, et al. (2023). Comparison of mixing plane, frozen rotor, and sliding mesh methods on a counter-rotating dual-rotor wind turbine. Applied Sciences, 13: 8982.
Tsang TW, Mui KW, Wong LT (2023). Computational Fluid Dynamics (CFD) studies on airborne transmission in hospitals: a review on the research approaches and the challenges. Journal of Building Engineering, 63: 105533.
Wang T, Han O, Yin H, et al. (2023). Study on the air distribution characteristics of equipartition-ring column attachment ventilation mode. Building Environment, 234: 110179.
WHO (2009). WHO guidelines for indoor air quality: Dampness and mold. World Health Organization.
WHO (2010). WHO guidelines for indoor air quality: Selected pollutants. World Health Organization.
Zavřel V, Zelenský P, Macia J, et al. (2022). Simulation aided development of a façade-integrated air handling unit with a thermoelectric heat exchanger. LIMA 2022, https://doi.org/10.34641/clima.2022.207.
Zelenský P, Barták M, Zavřel V, et al. (2019). Numerical analysis of air flow in a modular fan unit using CFD simulation. E3S Web of Conferences, 111: 01008.
Zender-Świercz E (2020). Improvement of indoor air quality by way of using decentralised ventilation. Journal of Building Engineering, 32: 101663.
Zmrhal V, Boháč J (2021). Pressure loss of flexible ventilation ducts for residential ventilation: Absolute roughness and compression effect. Journal of Building Engineering, 44: 103320.
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Zelenský, P., Zmrhal, V., Barták, M. et al. Simulation-aided development of a compact local ventilation unit with the use of CFD analysis. Build. Simul. (2024). https://doi.org/10.1007/s12273-024-1183-9
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DOI: https://doi.org/10.1007/s12273-024-1183-9