International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 02 | Feb-2018 www.irjet.net p-ISSN: 2395-0072 © 2018, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 571 A REVIEW OF PASSIVE TECHNIQUE USED FOR HEAT TRANSFER ENHANCEMENT IN HEAT EXCHANGER Ravindra M.Ghogare 1 , Vijay G.Gore 2 , A.S.Shaikh 3 1 Technical Assistant,Dept.of Mechanical Engineeering,NDMVPS’s COE,Nashik-13,Maharashtra,India 2,3 Assistant Professor, Dept.of Mechanical Engineeering,P.R.Pote(Patil)COE Amravati, Maharashtra,India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Enhancement in heat transfer rate can be done by numerous method in various heat exchangers.Heat exchangers may be chemical reactor,refrigeration system or air conditioning systems.So many techniques have been already investigated to improve heat transfer rate with reduced cost and size.One of the most important technique is Passive heat transfer technique.These technique gives best result for thermal performance.This paper reviews experimental and numerical works taken by the researchers on this technique since 2004, such as twisted tape,wire coil, swirl flow generator,etc… to improve the thermal performance of heat exchanger.The author found that number of developed twisted tape inserts are popular researched and are used to strengthen the heat transfer of specific heat exchanger equipment.Twisted tape inserts are more useful laminar flow than turbulent flow.Also the other technique involving ribs,conical nozzle and conical ring are more efficient for turbulent flow than laminar flow. Key Words: Heat transfer enhancement,Passive method,Inserts,Laminar & Turbulent flow 1.INTRODUCTION Heat exchangers are mostly used devices in many areas of the industries, such as process industries, heating and cooling in evaporators, thermal power plants, refrigeration and air-conditioning equipmentǯs, radiators for space vehicles, automobiles, etc. Increase in Heat Exchangers performance can lead to more economical design of the heat exchanger which can help to make energy, material & cost savings related to a heat exchange process. The need to increase the thermal performance of heat exchangers, there by effecting energy, material & cost savings have led to development & use of many techniques termed as Heat transfer augmentation. These techniques are also referred to call as Heat transfer Enhancement or Intensification. Augmentation techniques increase convective heat transfer by reducing the thermal resistance in a heat exchanger. In many literature gap shows the experimentation on perforated twisted insert like in experimental analysis of heat transfer characteristics using inserts in tubes. Heat transfer enhancement techniques refer to different methods used to increase rate of heat transfer without affecting much the overall performance of the system. Heat transfer augmentation techniques refer to different methods used to increase these techniques and broadly divided in two groups, passive and active. Active techniques involve some external power input for the enhancement of heat transfer. Passive heat transfer augmentation method does not use any external power input. One of the ways to enhance heat transfer performance in passive method is to increase the effective surface area and residence time of the heat transfer fluid. 2.DIFFERENT TECHNIQUES FOR HEAT TRANSFER ENHANCEMENT 2.1 Active method This method involves some external power input for the enhancement of heat transfer.Some examples of active methods include induced pulsation by cams and reciprocating plungers,the use of a magnetic field to disturb the seeded light particles in a flowing stream, mechanical aids, surface vibration, fluid vibration,electro-static fields, suction or injection and jet impingement requires an external activator/power supply to bring about the enhancement[1]. 2.2 Passive method This method generally uses a surface or geometrical modifica- tions to the flow channel by incorporating inserts or additional devices. For example, insertingan extra component, swirl flow devices, treated surface, rough surfaces, extended Surfaces, displaced enhancement devices, coiled tubes, surface tension devices and additives for fluids. [2] 2.3Compound method When any two or more techniques, i.e. passive and active may be employed simultaneously to enhance the heat transfer of any device, which is greater than that of produced by any of those techniques separately, the term known as Compound enhancement technique. The passive heat transfer augmentation methods as stated earlier do not need any external power input. For the convective heat transfer, one of the ways to enhance the heat transfer rate is to increase the effective surface area and residence time of the heat transfer fluids. The passive methods are based on this principle, by employing several techniques to generate the swirl in the bulk of the fluids and