【導(dǎo)讀】*作者通訊地址.納米流體已被報道為能夠加強熱的交換。外殼和螺旋盤管換熱器的性能已經(jīng)使用三個。水性納米流體實驗驗證。這些研究是在不同濃度的。納米流體，以及納米流體的溫度，攪拌速度和線圈側(cè)的流體溢流率進行的。流體的濃度為，，1，按重量計至2％的制備。殼側(cè)的值越高，熱交換器有越高的效率。當(dāng)與水進行對比時發(fā)現(xiàn)Al2O3，CuO和納米。TiO2/納米水的濃度在％，％和％時有最大增加率。該活躍的技術(shù)需要外部力量，例。器，核反應(yīng)堆和冷凝器也可用于在電廠。他們報道從彎管所得到的傳熱系數(shù)比從直。134a壓降與熱交換系數(shù)。他們報告說HFC-134a的熱轉(zhuǎn)換系數(shù)平均值隨著質(zhì)量通量，他報告說，冷水出口溫度，換熱器轉(zhuǎn)換率和平均傳熱。速率與熱水質(zhì)量流率的增加而增加。質(zhì)量通量和低壓條件下的關(guān)系。人們發(fā)現(xiàn)，壁間溫度和傳熱系。研究了從外側(cè)面強制對流與恒定的墻體通量螺旋盤管的關(guān)系。實驗結(jié)果表明，在水平處比垂直位置有更強的傳熱。其實驗結(jié)果表明，傳熱率提高與增加的線圈直徑，線圈

　　

【正文】 nditions. JamalAbad et al. [29] have experimentally investigated the performance ofaspiralcoilheatexchanger usingCu/waterandAl/ water nano?uids. It was found that the maximum thermal performance factor % vol. ofCu/water nano?uid. Thethermal performance factoristheratiooftheNusseltnumber ratio (NuNF/NuBF) to the friction factor ratio (fNF/fBF) at the same . Experimental setup diagram oftheexperimental setup usedinthepresent work[34]. Dimensions ofhelical coiltubeand withglasswooland shellside ?uid temperature was maintained constant using a temperature controller. Two 5kWelectrical heaters were used to heat the shellside ?uid, and temperature measurements were made using PT100typeRTDsensors. Anaxialturbine typestirrer (Make: RemiLaboratory Instruments, model: RQ121/D)wasused to(i)promoteheattransferfromtheshellside ?uidtothecoilside ?uid (water) by forced convection and (ii) maintain uniform temperature in the shell. Flow rate of the water through the coil wasmeasured usingrotameter (–5lpm).Thesetupisprovided withadataacquisition systemtorecordalltemperatures. Aswater ?owsthrough thecoil,heatistransferred fromtheshellside ?uid towater in the coil. pumping power. Jamshidi et al. [30] have experimentally investigated the performance of shell and helical tube heat exchangers by changing the coil diameter and pitch. Their experimental results indicated that heat transfer rate increased withincreaseincoildiameter, et al. [31] have experimentally investigated the heat transfer behavior between metal oxide nano?uid (Al O /water and TiO2/ . Experimental studies 2 3 water) ?ows through helical coiled tube with uniform heat ?ux boundary condition. They reported that the maximum thermal performance % Studies subsequently nano?uid on the shellside. The effect of coilside were carried out with water (base ?uid) and ?owrate(–5lpm),nano?uidconcentration (%,%,1%,% of Al O /water nano?uid through helical coiled tube heat 2 3 exchanger. Khairul et al. [32] have investigated the performance of a helically coiled heat exchanger using different types of nano?uids(CuO/water, Al O /waterandZnO/water). Theirexperi mental results showed that the maximum enhancement heat transfer coef?cient was %for 4% vol. of CuO/water. Table1 Details ofnanoparticles. 2 3 . Nanoparticle Manufacturer Size (nm) There have not been many studies in literature involving nano?uidsonshellside inshellandhelical 1 2 3 Al O3 CuO TiO2 SiscoResearch Laboratories Pvt.,Ltd.,India 20–30 2 SiscoResearch Laboratories Pvt.,Ltd.,India MKnano, USA 40 10 the literature cited above, researchers [12,30] have used , A. VenuVinod/Chemical Engineering and Processing 102(2021)1–8 3 . Schematic diagram of the experimental setup [36]. ix. The experiment was repeated for other stirrer speeds, shell side ?uid temperatures and nano?uids. Table2 Details ofshell and helical coil tube. Dimensions ofhelical coil tube and shell 3. Theory/calculation procedure Internal coil diameter (m) External coil diameter (m) Coilheight(m) Inner diameter of the tube (m) Outer diameter of the tube (m) Coil pitch (m) Length of the coil tube (m) Numberof turns Shellheight(m) 6 10 exchanger effectiveness (e) Heattransferinthepresentstudyoccurredfromthehot?uidin theagitated thermophysical properties of coilside ?uid (water) were evalu ated at average temperature of the inlet and outlet. The heat transferred tothecoilside ?uidisequaltotheheatgained bythe ?uid, which is calculated from the following equation. Shell diameter (m) Q 188。m_ C DT 240。1222。 and 2%wt.) ofAl O ,CuO and TiO nano?uids, stirrer speed (500, 1000 and 1500rpm) and shellside ?uid temperature (40, 45 and p 2 3 2 50C)onheat transfer from shellside tocoilside wasinvestigat ed. Qmax 188。m_Cp240。Ts192。Tci222。 240。2222。 where, m_ =mass ?ow rate, C =speci?c heat, T =coilside ?uid p ci . Experimental procedure inlet temperature, Tco=coilside ?uid outlet temperature, DT= temperature difference=(Tco–T ), T =shellside ?uid tempera i. Theshellwas?lledwithbase?uid,ultrapurewater(deionized and demineralized water, (conductivity ) from Millipore Ultrapure water system). ii. Stirrer wasswitched onandthespeed wassetataparticular value (500, 1000 and 1500rpm). ci s effectiveness oftheheatexchanger isde?nedastheratio of the actual heat transfer rate to the maximum possible heat transfer rate. Effectiveness of heat exchanger is calculated from equation iii. Heaters were switched on to heat the shell side ?uid to required temperature (40, 45 and 50C). iv. Pumpwasswitched onandthe?owrateofwaterthroughthe Q Qmax e188。 240。3222。 helical coil was set at using rotameter. . Dean number and Reynolds number v. Shell side temperature was maintained constant using temperature controller and the experiment was allowed to run in steady state (as indicated by constant shellside ?uid temperature). vi. At steady state, outlet temperature of coilside ?uid (water) was noted. vii. The ?ow rate of the water through the coil was increased to 1lpm and steps (v)and (vi) wererepeated upto5lpm inthe increments of . viii. Nowthesteps from (ii)to(vii) wererepeated with nano?uid of different concentrations on shellside. Dean number was calculated using the following equation: 05 d 2R : i 4 5 De188。Re 240。 222。 c dvr m i Re188。 240。 222。 4 , A. VenuVinod/Chemical Engineering and Processing 102(2021)1–8 where,d isinnerdiameterofthecoiltube,R iscurvatureradiusof i c the coil and v velocity of the ?uid through the coil. Viscosity (m) and density (r)ofthe?uid havebeen evaluated atthe average of the inlet and outlet temperatures of the coilsid