FAN COIL ISI EŞANJÖRÜNÜN FARKLI KOLEKTÖR TASARIMININ SU BASINÇ KAYBINA ETKİSİ VE DENEYSEL İNCELENMESİ

Abstract

Bu çalışmanın amacı, fan coil ısı eşanjörlerinde farklı kolektör tasarımlarının su tarafı basınç kaybı üzerindeki etkilerini deneysel olarak incelemektir. Boru çapı (Ø16, Ø22, Ø25 mm), uzunluğu ve devre sayısı (2NC, 4NC) parametrelerinin etkileri, hava entalpi laboratuvarında 0,150–2,000 m³/h debi aralığında beş farklı grup (A, B, C, D, E) üzerinde test edilmiştir. Test sonuçlarına göre, 2NC yapılı A, B, C ve D gruplarında çap arttıkça ΔP artışı gözlenmiştir. C grubunda çapın Ø16’dan Ø25 mm’ye çıkarılması orta debilerde 1,0–2,0 kPa basınç artışına neden olurken; 4NC yapılı E grubunda aynı çap artışı 1,0–2,0 kPa basınç azalması sağlamıştır. Ayrıca E grubu, akış dengesi sayesinde C grubuna kıyasla basınç kaybını yaklaşık üç kat düşürerek en iyi performansı göstermiş ve teorik değerlerle uyum sağlamıştır. Sonuç olarak, kolektör tasarımında sadece boru çapını değiştirmenin yeterli olmadığı; devre sayısı, akış dengesi ve geometrik yerleşimin optimizasyon için belirleyici faktörler olduğu belirlenmiştir. Bu çalışma, maliyet etkinliği yüksek ve hidrolik performansı geliştirilmiş fan-coil tasarımlarının elde edilmesi için tasarımcılara yol gösterici veriler sunmaktadır.

Keywords

• Devre sayısı (NC)
• Kolektör boru geometrisi
• Fan coil
• Hidrolik performans
• Su basınç kaybı

Effect of Different Collector Designs on Water Pressure Loss and Experimental Investigation of the Fan Coil Heat Exchanger

Abstract

The aim of this study is to experimentally investigate the influence of collector design parameters on water-side pressure loss in fan coil heat exchangers. Pipe diameters (Ø16, Ø22, Ø25 mm), collector lengths (180 and 240 mm), and circuit numbers (2NC and 4NC) were evaluated through laboratory tests conducted on five different configurations over a flow range of 0.150–2.000 m³/h. The results show that for 2NC configurations, increasing pipe diameter led to a rise in pressure loss (ΔP), whereas in the 4NC configuration the same diameter increase resulted in a reduction in ΔP due to improved flow distribution. The 4NC design exhibited the lowest pressure losses, approximately one-third of those observed in comparable 2NC designs. Main-effect analysis revealed a clear sensitivity hierarchy among the investigated parameters: number of circuits (NC) >> diameter (D) > length (L). While the circuit number produced an average ΔP difference of approximately 35 kPa between 2NC and 4NC levels, the diameter effect remained within 1–3 kPa and the length effect below 1.5 kPa across the investigated range. The findings indicate that hydraulic performance in fan coil collectors is governed primarily by flow redistribution associated with circuit configuration rather than by simple geometric scaling of pipe diameter. These results provide quantitative support for optimizing collector design based on flow balance and cost-performance considerations.

Keywords

• Number of circuits (NC)
• Collector pipe geometry
• Fan coil unit
• Hydraulic performance
• Total water pressure loss

Supporting Institution

This research received no external funding.

Ethical Statement

This article does not contain any studies involving human participants or animals.

Thanks

The authors would like to thank Daikin Heating and Cooling Systems Industry and Trade Inc., Sakarya, Turkey and the R&D Cooling Reliability team members for the technical support and facilities provided during the experimental studies.

References

1. ASHRAE. (2017). ASHRAE handbook—Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers.
2. ASHRAE. (2021). ASHRAE handbook—Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers.
3. Bretado-de los Rios, M. S., Rivera-Solorio, C. I., Gijón-Rivera, M. A., & Nigam, K. D. P. (2022). Experimental evaluation of the thermal and hydrodynamic performance of nanofluids in a coiled flow inverter. Chemical Engineering and Processing - Process Intensification, 180, Article 108957. https://doi.org/10.1016/j.cep.2022.108957
4. CHINO Corporation. (2023). General specification: Resistance thermometers [Technical document].
5. Crane Co. (2018). Flow of fluids through valves, fittings, and pipes (Technical Paper No. 410).
6. Hwang, Y. W., & Kim, M. S. (2006). The pressure drop in microtubes and the correlation development. International Journal of Heat and Mass Transfer, 49(11–12), 1804–1812. https://doi.org/10.1016/j.ijheatmasstransfer.2005.10.040
7. Idelchik, I. E. (1994). Handbook of hydraulic resistance (3rd ed.). Begell House.
8. International Organization for Standardization. (2024). Guide to the expression of uncertainty in measurement—Part 1: Introduction (ISO/IEC Guide 98-1:2024).

9. Khunphakdee, P., Phuakpunk, K., Piemjaiswang, R., & Chalermsinsuwan, B. (2025). Design optimization of a high-pressure economizer header in heat recovery steam generators to mitigate flow-accelerated corrosion. Results in Engineering, 26, Article 105321. https://doi.org/10.1016/j.rineng.2025.105321
10. Lecardonnel, A., Falsetti, C., Tempesti, C., & Laboureur, D. (2025). About two-phase flow distribution improvement in the header of a simplified evaporator: A multi-factorial study with the help of a design of experiment technique. Applied Thermal Engineering, 279, Article 128034. https://doi.org/10.1016/j.applthermaleng.2025.128034
11. Maddah, H., & Ghasemi, N. (2017). Experimental evaluation of heat transfer efficiency of nanofluid in a double pipe heat exchanger and prediction of experimental results using artificial neural networks. Heat and Mass Transfer, 53(12), 3459–3472. https://doi.org/10.1007/s00231-017-2068-6
12. Men, Z., Chen, W., Hu, Q., & Liu, S. (2024). Numerical and experimental investigation of a multi-channel heat sink distribution header designed by topology optimization. Applied Thermal Engineering, 238, Article 122008. https://doi.org/10.1016/j.applthermaleng.2023.122008
13. Peng, X. F., & Peterson, G. P. (1996). Convective heat transfer and flow friction for water flow in microchannel structures. International Journal of Heat and Mass Transfer, 39(12), 2599–2608. https://doi.org/10.1016/0017-9310(95)00327-4
14. Swamee, P. K., & Jain, A. K. (1976). Explicit equations for pipe-flow problems. Journal of the Hydraulics Division, 102(5), 657-664. https://doi.org/10.1061/JYCEAJ.0004542
15. Taguchi, G. (1993). Taguchi on robust technology development: Bringing quality engineering upstream. ASME Press.
16. Yokogawa Electric Corporation. (2020). ADMAG TI Series AXG magnetic flowmeter general specifications.
17. Yokogawa Electric Corporation. (2021). EJA110E differential pressure transmitter general specifications.