© 2021 JETIR October 2021, Volume 8, Issue 10 www.jetir.org (ISSN-2349-5162) JETIRFD06008 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 69 STUDY AND ANALYSIS OF AIR FLOW THROUGH DUCT Sulekha Walunj 1 , Shantanu Shirsath 2 , Avinash Biradar 3 , Asawari Salvi 4 , Mansi Deore 5 1 (Assistant Professor, Department of Mechanical Engineering, Terna Engineering College, Navi Mumbai, India) 2,3,4,5 (Students, Department of Mechanical Engineering, Terna Engineering College, Navi Mumbai, India) ABSTRACT: Air conditioning systems are considered operating successfully based on the efficient supply of air in the air-conditioned space. Estimation of pressure losses in ducts is vital for the selection of duct size. The installation cost of duct in air conditioning system is about 20 to 30% of the total cost of equipment selection and power consumption of supply fans also adds to the running cost. Hence, it’s important to minimize the capital and running cost of the duct system. Duct design is the design of enclosed passage for supplying conditioned air and then distributing the sir to specified areas according to the need. There are various advantages of efficiently designed and constructed interior ducts. One of the advantages is enhanced energy efficiency through the cancellation of duct leakage and reducing conductive heat gains/losses. This paper focuses on a study of design and improving air duct using computational fluid dynamics (CFD) analysis considering all the parameters related to air flow and its characteristics for enhancing duct system efficiency. The necessity of optimization of duct system is to improve supply air flow. It integrates theoretical and software tools to provide detailed comparative analysis of the advantages involved in selecting a particular shape (rectangular duct with Y-shaped bend and with 90-degree corner with sharp bend) of duct for a specified conditions. The focus of this paper will be on using CFD simulation tools to study velocity distribution of air in the duct at various sections, pressure difference at various outlets and distributions of air flow. Keywords- Duct design, Duct system, HVAC, Pressure Distribution, Velocity Profile 1. INTRODUCTION An air conditioning duct is an enclosed passage or part that is used for the distribution of air throughout the air-conditioned space. Duct system also known as ductwork is a central part of Heating, Ventilation and Air Conditioning (HVAC) system. In duct systems, two set of ductworks are present, which is used to supply cool air and return air from air-conditioned space, also there is provision for general ventilation needs [1]. The purpose of the ducting system is to transfer the air from air handling unit to the area which needs to be air conditioned. The flow of air is due to the pressure difference created by the fan fitted in the air handling unit or the duct. The pressure difference which is responsible for the transport of air from one location to another reduces due to various fittings in the ducts (eg. Filters), bends present in the duct and also due to friction between air and duct surface [2]. When the working fluid (air) travels through the duct fittings the velocity and pressure profiles are disrupted (figure 1). The distortion of velocity profiles is caused by geometric conditions of the duct. There is rise of eddy zone in the fittings, which affect the shape of velocity profile (figure 1). After the fluid passes the duct fitting, the velocity profile tries to realign. The phenomenon mentioned above (distortion of the velocity profile) caused the local pressure loss [3].The amount of pressure loss in a system is directly proportional to the amount of energy consumed by the Fan in overcoming the loss in pressure. Thus, it becomes necessary to reduce the pressure losses in a ducting system. Figure 1: velocity profiles in a duct with an elbow [3] For reducing the pressure losses in the duct system circular cross sectional ducts can be used instead of conventional rectangular ducts [4] however fabrication and installation of circular ducts is complicated and expensive. Also divergence can be provided for changing the direction of air flow instead of sharp 90° bend [5].