Modelling and Optimization of Direct Expansion Ac

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Applied Energy 87 (2010) 1158–1175

Contents lists available at ScienceDirect

Applied Energy
journal homepage: www.elsevier.com/locate/apenergy

Energy efficient fuzzy based combined variable refrigerant volume and variable air volume air conditioning system for buildings R. Karunakaran a, S. Iniyan b,*, Ranko Goic c
a

Department of Mechanical Engineering, Anna University Tiruchirappalli-Thirukkuvalai campus, India Institute for Energy Studies, Department of Mechanical Engineering, Anna University Chennai, Chennai, India c Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Split, Croatia b

a r t i c l e

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a b s t r a c t
Energy conservative building design has triggered greater interests in developing flexible and sophisticated air conditioning systems capable of achieving enhanced energy-savings potential without sacrificing the desired thermal comfort and indoor air quality (IAQ). This research work greatly aimed at achieving enhanced energy conservation, good thermal comfort and better IAQ for space conditioning with the application of combined variable refrigerant volume (VRV) and variable air volume (VAV) air conditioning (A/C) systems. Experimental investigation on the proposed combined air conditioning system with the application of intelligent fuzzy logic controller was performed for summer and winter climatic conditions to substantiate the energy-savings capability. The proposed system experimentally analyzed under fixed ventilation, demand controlled ventilation (DCV) and combined DCV and economizer cycle (EC) ventilation techniques effectively conserved 44% and 63% of per day average energy-savings in summer and winter design conditions respectively, while compared to the conventional constant air volume (CAV) A/C system. The results of the present investigation have proved that the proposed combined air conditioning system operated under the different ventilation strategies and controlled by the intelligent fuzzy logic controller (FLC) can be considered as an efficient technology to achieve good thermal comfort, IAQ and energy conservation in the modern heating, ventilation and air conditioning (HVAC) applications. Ó 2009 Elsevier Ltd. All rights reserved.

Article history: Received 26 September 2008 Received in revised form 6 August 2009 Accepted 12 August 2009 Available online 19 September 2009 Keywords: Energy conservation Fuzzy logic Indoor air quality Thermal comfort Ventilation Variable refrigerant volume Variable air volume

1. Introduction For over a century, the heating, ventilation and air conditioning (HVAC) community has witnessed a quantum leap in the field of design and value added renovations in air conditioning (A/C) engineering. The prime factors to be indisputably considered as the four pillars of the HVAC system are, thermal comfort, indoor air quality (IAQ), HVAC controls and energy-savings. The part played by humidity in the perception of thermal comfort cannot be exaggerated, as minor shifts in RH will have a sharp impact on microbial growth, in particular, at lower RH levels i.e. less than 30%. The thermal comfort and IAQ inside the building envelope can be obtained by properly monitoring the supply air temperature and supply airflow rate based on the fluctuated thermal load conditions. Energy usage in air conditioning systems is considered an essential part of a building’s functional requirements. Since the late

* Corresponding author. Tel.: +91 44 22531070. E-mail addresses: karuna30722@yahoo.com (R. Karunakaran), iniyan777@ hotmail.com (S. Iniyan), rgoic@fesb.hr (R. Goic). 0306-2619/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2009.08.013

1960s, however, HVAC engineers have begun to explore various design concepts to minimize energy use in air handling systems. The major drawback of the constant volume systems is that they generally use more energy. Variable volume...
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