Techno-Economic Assessment of Heat Recovery in Series Condensers Arrangement: Hot and Humid Regions

Document Type : Research Article


1 Department of Energy Engineering, Sharif University of Technology, Tehran, Iran

2 Department of Renewable Energy and Environment, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran


A direct expansion (DX) HVAC system is an efficient way to supply fresh and dehumidified air to a built environment. To improve the efficiency of a conventional DX system in hot and humid regions, fresh air dehumidification and conditioning systems with energy recovery measures are the key equipment to reach such a goal. To achieve this goal an integrated system is proposed. The integrated system substitutes the reheat coil with an extra condenser in series arrangement with the main condenser to reheat the supply air while mixing the ventilated air with condenser cooling air. Modeling has broken down into two parts. Psychometric part which has been modeled using EnergyPlus and EES software, and DX system in which data is received via psychometric part, and has been modeled and evaluated by EES software. The case study is located in Bandar-e-Abbas city, quasi-dynamic modeling is to be conducted and results will be analyzed correspondingly. The integrated system’s energy saving is 32-48%. Also, system’s COP has increased from 1.55 to 3.46 for outside air fraction (ventilation rate) of 0%, and from 2.37 to 3.47 for outside air fraction of 100%. Finally the payback period is roughly less than 4 years.


Barbosa, J. R., Melo, C., Hermes, C. J. L., and Waltrich, P. J. (2009). A study of the air-side heat transfer and pressure drop characteristics of tube-fin “no-frost” evaporators. Applied Energy, 86(9): 1484–1491.
Bejan, A., and Tsatsaronis, G. (1996). Thermal design and optimization. John Wiley & Sons.
Bell, I. H., and Groll, E. A. (2011). Air-side particulate fouling of microchannel heat exchangers: Experimental comparison of air-side pressure drop and heat transfer with plate-fin heat exchanger. Applied Thermal Engineering, 31(5): 742–749. 
Cuce, P. M., and Cuce, E. (2017). Toward cost-effective and energy-efficient heat recovery systems in buildings: Thermal performance monitoring. Energy, 137: 487–494. 
Cuce, P. M., Cuce, E., and Riffat, S. (2016). A novel roof type heat recovery panel for low-carbon buildings: An experimental investigation. Energy and Buildings, 113: 133–138.
Diao, Y. H., Liang, L., Kang, Y. M., Zhao, Y. H., Wang, Z. Y., and Zhu, T. T. (2017). Experimental study on the heat recovery characteristic of a heat exchanger based on a flat micro-heat pipe array for the ventilation of residential buildings. Energy and Buildings, 152: 448–457.
Gnielinski, V. (1976). New equations for heat and mass transfer in turbulent pipe and channel flow. Int. Chem. Eng., 16(2): 359–368.
Jeong, J.-W., and Mumma, S. (2003). Energy conservation benefits of a dedicated outdoor air system with parallel sensible cooling by ceiling radiant panels. ASHRAE Transactions, 109(2): 627–636.
Li, X. Y., Li, Z. H., and Tao, W. Q. (2018). Experimental study on heat transfer and pressure drop characteristics of fin-and-tube surface with four convex-strips around each tube. International Journal of Heat and Mass Transfer, 116: 1085–1095. 
Liang, C. H., Zhang, L. Z., and Pei, L. X. (2010). Performance analysis of a direct expansion air dehumidification system combined with membrane-based total heat recovery. Energy, 35(9): 3891–3901.
Manz, H., and Huber, H. (2000). Experimental and numerical study of a duct r heat exchanger unit for building ventilation, 189–196.
McQuiston, F. C., and Parker, J. D. (1982). Heating, ventilating, and air conditioning: analysis and design.
Naphon, P. (2010). On the performance of air conditioner with heat pipe for cooling air in the condenser. Energy Conversion and Management, 51(11): 2362–2366. 
Pérez-Lombard, L., Ortiz, J., and Pout, C. (2008). A review on buildings energy consumption information. Energy and Buildings, 40(3), 394–398.
Ramadan, M., El Rab, M. G., and Khaled, M. (2015). Parametric analysis of air-water heat recovery concept applied to HVAC systems: Effect of mass flow rates. Case Studies in Thermal Engineering, 6: 61–68.
Roulet, C. A., Heidt, F. D., Foradini, F., and Pibiri, M. C. (2001). Real heat recovery with air handling units. Energy and Buildings, 33(5): 495–502.
Schmidt, T. E. (1949). Heat transfer calculations for extended surfaces. Refrig. Eng, 57(4): 351–357.
Vakiloroaya, V., Samali, B., Cuthbert, S., Pishghadam, K., and Eager, D. (2014a). Thermo-economic optimization of condenser coil configuration for HVAC performance enhancement. Energy and Buildings, 84: 1–12.
Vakiloroaya, V., Samali, B., Fakhar, A., and Pishghadam, K. (2014b). Thermo-economic optimization of rooftop unit’s evaporator coil for energy efficiency and thermal comfort. Building Simulation, 7(4): 345–359.
Wang, C.-C., and Chi, K.-Y. (2000). Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, part I: new experimental data. International Journal of Heat and Mass Transfer, 43(15): 2681–2691.
Wang, C.-C., Chi, K.-Y., and Chang, C.-J. (2000). Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, part I: new experimental data. International Journal of Heat and Mass Transfer, 43(August 2000), 2693–2700.
Warden, B. D. (2004). Supply Air CO 2 Control. ASHRAE Journal, 46(October).
Yau, Y. H. (2008). The use of a double heat pipe heat exchanger system for reducing energy consumption of treating ventilation air in an operating theatre-A full year energy consumption model simulation. Energy and Buildings, 40(5), 917–925.
Zhang, Z.-Y., Zhang, C.-L., Ge, M.-C., and Yu, Y. (2018). A frost-free dedicated outdoor air system with exhaust air heat recovery. Applied Thermal Engineering, 128: 1041–1050.