Design, Development and Experimental Investigation of Volumetric Air Receiver

Transcription

1 International Engineering Research Journal (IERJ) Special Issue 2 Page ISSN ISSN Design Development and Experimental Investigation of Volumetric Air Receiver #1 S.N.Tupe #2 P.M. Gadhe 1 siddhant.tupe@gmail.com 2 prakash.gadhe@mitpune.edu.in #1 Department of Mechanical EngineeringMAEER s MIT Savitribai Phule Pune University PuneMaharashtra India #2 Department of Mechanical EngineeringMAEER s MIT Savitribai Phule Pune University Pune Maharashtra India ABSTRACT There are different types of receivers and their testing is done in different parts of world. A lot of research is done on cavity receiver and tubular receiver.very less work is done on volumetric air receiver. The volumetric receiver is a body with porous interlocking shapes knit-wire packs foam or foil arrangements. The receiver may be made of metal ceramic or some other materials (based on material properties such as thermal conductivity) with a specific porosity so that the concentrated solar radiation that is reflected by a collector is absorbed in the depth of the structure. The concentrated solar radiation is focused on one end of the receiver. The radiation heats the material through absorption in the volume. Air is sucked from atmosphere in this receiver through the pores from one side and heat is transferred to the relatively cold air through the surface by convection. As a result of direct exposure of the front side of porous body to cold ambient its is lower than that of the inner volume. Lower at the front face of volumetric receivers (porous body) reduces the radiation loss to atmosphere. Such volumetric air receiver is designed in which air is to be sucked with the help of centrifugal blower. Scheffler reflector of area 2.7 is used as collector for reflecting solar radiation on volumetric air receiver. Reflector is small lateral section of much larger paraboloid that produces typical elliptical shape of scheffler reflector.the performance of scheffler collector system depends upon various thermal and optical properties receiver geometry and orientation of the system with respect to sun position in the sky. Inlet and outlet of air receiver is measured with the help of resistance thermometer. The main aim is to increase the outlet of air receiver.volumetric air receiver has applications for electricity productions industrial process heat and chemical processing. Keywords VAR Scheffler reflector. ARTICLE INFO Article History Received :18 th November Received in revised form : 19 th November Accepted : 21 st November Published online : 22 nd November I. INTRODUCTION R Sharma P Sharma et al performed the design and evaluation of an open volumetric air receiver which can be used for aluminium heat treatment system. They designed three configuration of receiver hexagonal circular and square in shape.they performed detail design calculation of various parts of receiver such as mixer plate which is used for creating turbulence footpiece which is to be used for holding receiver and convergent nozzle and also did their IERJ All Rights Reserved Page 1

2 International Engineering Research Journal (IERJ) Special Issue 2 Page ISSN CFD analysis.[1]laltu Chandra Rajiv Shekhar et al performed the design and evaluation of open volumetric air receiver for process heat applications. This technology includes thermal energy storage and heat exchanger system a computational fluid dynamics namely ANSYS-FLUENT is utilized for evaluation purpose. The obtained hot air can be employed for metal processing application. The design aspect of volumetric air receiver are influence of material property on air receiveranalysis of heat transfer experiment with porous body and flow instability of air receiver.[2].z.d. Cheng Y. L.He et al performed the numerical investigations on coupled heat transfer and synthetical performance of a pressurized volumetric receiver with MCRT-FVM method.they presented an axisymmetric steady state computational fluid dynamics model and further studies on the complex coupled heat transfer combined radiation convection conduction in pressurized volumetric receiver by combining finite volume method and Monte Carlo rat trace method.[3].zhiyong Wu Cyril Caliot et al performed the numerical simulation of convective heat transfer between air flow and ceramic foams to optimize volumetric solar air receiver performances. Porous ceramic foams are used to achieve high performance solar heat recovery system.their approach was to compute the local convective heat transfer coefficient between air flow and porous ceramic foam.[4].zhinyong WuZhifeng Wang performed the fully coupled transient modelling of ceramic foam volumetric solar air receiver.the pressure drop of the absorber interfacial heat transfer between flowing fluid and solid and the radiative heat transfer due to concentrated solar radiation absorption by ceramic foam and radiation transport inside the media were included together in this transient model.[5].thomas Frend described the solar tower technology and volumetric air receiver briefly.[6] James Chavez Cristina Chaza performed the work on results of design and testing of a porous ceramic absorber for volumetric air receiver.they designed this new volumetric air absorber to use a porous ceramic material.the ceramic absorber was tested at plataforma solar de America with solar flux of up to 1200kw/. It produced outlet air of 730.[7] II. DESIGN CALCULATION Minimum velocity of air =5.5 m/s By using blower we doubled the velocity of air=11.11m/s Input falling on surface of receiver =80 Collector area =2.7 Total available energy= =1350 w Area of receiver = 3.14/ = Rate of heat loss from air to receiver Q=m (1) Mass flow rate of air = VA= kg/s For unit square area Q= m. ( - ) ( 2) 0.500= ) =104.7 =Outlet of air out of ring without brass modules By using Zukusaw relation Nu=C (3) Reynolds number Re= Prandtl number Pr=.715 Nusselt number Nu=17.16 Convective heat transfer coefficient h= w/mºk Rate of heat transfer by convection assuming 18 % losses h= (4) = =Outlet of air out of ring with brass modules Inner diameter of nozzle =48mm Area of bigger nozzle =1.809 Outer diameter of nozzle =20mm Area of smaller nozzle=3.14 = Applying Bernoulli equation P1/ + = P2/ + (5) R /g + = R /2g + (6) hot air at outlet of receiver=345 Figure 2.1: Volumetric air receiver- 1.Brass module2.footpiece 3.Ring 4.Recirculatingpipe 5.Footpieceholding plate 6.Mixer casing 7.Mixer plate 8.Convergent nozzle Absorber: Porous material used is brass of 12 mm in diameter each and 2.5mm its pore diameter.there are 7 holes in each module. Such 7 porous bodies are fixed in ring. Solar radiation falls on this porous body Foot-piece: Foot-piece is used for holding 7 brass receiver modules Recirculating Pipes: These are used for circulating excess heat in receiver to the system 2.4. Foot-piece Holding Plate: Foot-piece holding plates are used for holding foot-piece into receiver 2.5. Mixer Plate: It is the perforated plate which aids in creating turbulence for mixing of the non-uniformly heated air Convergent Nozzle: It is used for complete mixing of the air flowing out of all the individual receivers. Mixer casing is used for locating foot-piece holding plate and mixer plate. IERJ All Rights Reserved Page 2

3 International Engineering Research Journal (IERJ) Special Issue 2 Page ISSN Figure 3.2: Volumetric Air Receiver Figure 2.2: All dimensions of various parts of receiver in 2D 2.7.Scheffler Reflector: The reflector is a small lateral section of a much larger paraboloid. The inclined cut produces the typical elliptical shape of the Scheffler-Reflector. The sunlight that falls onto this section of the paraboloid is reflected sideways to the focus located at some distance of the reflectors. Scheffler reflector of aperture area of 2.7 is used as collector.[8] 2.8. Blower:Centrifugal blower is used for suction of hot air at receiver outlet of 90 cubic feet per minute of constant mass flow rate. Specifications of blower are 15 watt 230VAC 1-Ph.18 A 2800 rpm and 90CFM.Flow rate of air in blower without gear arrangement is 0.15 /s and that of gear arrangement of ratio 1:2 is 0.10 /s. Flow rate of air for gear ratio 2:1 is 0.23 /s [9]. III. EXPERIMENTAL SET UP AND PROCEDURE: Experimental set up is as shown in figure 3.1 model of volumetric air receiver is also shown figure 3.2 Figure 3.3: Volumetric Air Receiver with Recirculating Arrangement Figure 3.1.Experimental Setup Figure3.4: VAR with Gear Arrangement of ratio 2:1 Firstly volumetric air receiver is placed in front of scheffler reflector at distance of 2 to 3 m. Scheffler reflector is adjusted in accordance with sun so that its focus falls on receiver diameter. Blower is turned on which is used for sucking of hot air which is fitted to pipe.pipe is connected to outlet of receiver. Outlet of air is measured with the help of resistance thermometer. Ambient air IERJ All Rights Reserved Page 3

4 International Engineering Research Journal (IERJ) Special Issue 2 Page ISSN is measured with the help of thermocouple which is taken as inlet air. Readings are taken for every 15 minutes readings are taken in four stages as shown in observation tables and 4.readings are taken in month of May and June. 1) Stage 1- VAR without recirculating arrangement table 1.(2800 RPM) Ambient air of receiver Radiation speed m/s Time 3 June Ambient air of receiver Radiation speed m/s Time Hr a.m a.m a. m a.m p.m p.m p.m p.m p.m p.m p.m p.m. 2 nd a.m a.m a. m a.m p.m p.m p.m. 3)Stage 3 -VAR with gear arrangement of ratio 2:1 Table 3(5600 RPM) Ambient air Radiation Time of receiver speed m/s 6 nd a.m a.m a. m a.m p.m p.m p.m p.m p.m p.m p.m p.m. 4) Stage 4 - VAR with gear arrangement of ratio 1:2 table 4(1400 RPM) Ambient air of receiver Radiation speed m/s Time p.m p.m p.m p.m p.m a.m a.m a. m a.m p.m p.m p.m p.m p.m p.m p.m p.m. 2)Stage 2- VAR with recirculating arrangement table 2(2800 RPM) IERJ All Rights Reserved Page 4

5 International Engineering Research Journal (IERJ) Special Issue 2 Page ISSN GRAPH 1. TEMPERATURE DIFFERENCE VS TIME PERIOD Graph 1 shows variation of difference between ambient air and receiver outlet air.i t is observed that we get less difference in stage 3 as we go on increasing the flow rate of air and on increasing the rpm of blower for gear ratio 2:1 compared to other stages. In stage 4 we get maximum difference as we reduced the flow rate of air and reduced the rpm of blower for gear ratio 1:2.In stage 2. we get slight increase in compared to stage 1 from all four stages it is observed thatas we go on increasing the flow rate of air we got less difference because there is less time for the air to heat transfer conversely as we go on decreasing the flow rate of air we got maximum difference because there is more time for air to heat transfer. IV. CONCLUSIONS It is observed that in stage 1 without recirculating arrangement maximum hot air obtained is 53.In second stage with recirculating arrangement Maximum obtained is 56. In 3 rd stage VAR with gear arrangement of ratio 2:1 of air get decreased. VAR with gear ratio 1:2 maximum s obtained is 59. It is observed that with recirculating arrangement there is slight increase in air as in it mass flow rate get distributed compared to without recirculating arrangement.it is also observed that as RPM of blower decreases there is slight increase in of hot air. It is also Theoretically we are getting hot air in range of Experimentally we got hot air in range because losses are their like environmental lossesmaterial losses dimension losses etc. ACKNOWLEDGMENT Thankful to Prof P.M.Gadhe for his valuable contribution in developing this paper and proper guidance [3] Z.D.Cheng F.Q.Cui Numerical Investigations on Coupled Heat Transfer and Synthetical Performance of a Pressurized Volumetric Receiver with MCRT-FVM Method. (2012). [4]Zhiyong WuCyril Caliot Numerical Simulation of Convective Heat Transfer Between Air Flow and Ceramic Foams To Optimize Volumetric Solar Air Receiver Performances. (2011) [5]Zhinyong Wu Zhifeng Wang Fully Coupled Transient Modeling of Ceramic Foam Volumetric Solar Air Receiver (2012). [6]Thomas Fend High Porosity Materials As Volumetric Receivers For Solar Energetics. (2010) [7]James Chavez Cristina Chaza Results of the design and testing of a porous ceramic absorber for a volumetric air receiver. [8]Jason Rapp Dr Peter Schwartz Construction and improvement of a scheffler reflector and thermal storage device. (2010). [9]How to select right fan or blower sunon technology. NOMENCLATURE Minimum velocity of air= m/s Input falling on surface of receiver= Collector area= Total available energy=q w Area of receiver= Mass flow rate of air= kg/s Outlet of air out of ring without brass modules = Reynolds number= Re Prandtl number =Pr Nusselt number= Nu Convective heat transfer coefficient =h w/mºk Outlet of air out of ring withbrass modules Inner diameter of nozzle= mm Area of bigger nozzle= Outer diameter of nozzle mm Area of smaller nozzle= Hot air at outlet of receiver= Gas constant=r J/kgºK c.m=constant RPM= revolution per minute CFM= cubic feet per minute VAR =volumetric air receiver REFERANCES [1] Piyush SharmaLalatu Chandra On the design and evaluation of open volumetric air receiver for process heat applications. (2014). [2] Piyush Sharma L.chandra R. Shekhar Solar Tower Based Aluminium Heat Treatment System: Part1. Design and Evaluation of An Open Volumetric Air Receiver. (2014). IERJ All Rights Reserved Page 5