33 7 2017 7 Vol.33,No.7 Jul.2017 DOI10.13652/j.issn.1003-5788.2017.07.027 Stimulationandtheoreticalanalysisofheattransferduringthe freezingprocesssimulationofbeef 1,2 1,2 1,2 1,2 TANG Wan 1,2 WANG Jin-feng 1,2 LI Wen-jun 1,2 XIE Jing 1,2 (1., 201306;2., 201306) (1.ShanghaiEngineering Research Centerof Aquatic ProductProcesing & Preservation,Shanghai201306,China; 2.Colegeof Food Scienceand Technology,ShanghaiOcean University,Shanghai201306,China) [1-2] (CFD),, [3], (T1 T2 T3 T4 T5) 5.45%,3.90%,5.80%, Pham Q T [4] 4.24%,9.60% 1.79, BeckerB R [5] ; ; ; AbstractFreezingisrecognizedasoneoftheimportanttechnologyin foodpreservation.consideringthechangeofphysicalcharacteristics inbeefundertheprocessofthefreezing,theequivalentheatcapacity methodwasutilizedtoprocesslatentheatinphasechange,andthen thecomputationalfluiddynamics (CFD)numericalsimulationtech- dictthebeeftofreezetimewel. nologywasappliedtosimulatethefreezingprocessandestablishthe diferentialequations ofthree dimensionalfoodfreezing process. Through the numerical simulation of freezing time,the error betweeneachexperimentalmeasuringpoint (T1,T2,T3,T4and T5)valueandsimulationcalculationoffreezingtimeweredetectedto be5.45%,3.9%,5.8%,4.24%,5.8%,respectively,andeach pointtemperaturereal-timesimulation oftheaverageerror was 1.79.Theresultsshowedthatthenumericalsimulationcouldpre- Keywordsnumericalsimulation;freezingtime;foodfreezing;re- frigerator ( 2016YFD0400303); ( 16DZ2280300) [11], (1968 ), E-mailjxie@shou.edu.cn 2017 05 09 ( ) CFD [6-7], [8] [9], C Pham Q T [10] 3,, [12] [13], Basic 117
2017 7 ρc T, t = (k T)+q (1) (1) Fluent15.0 q=h(tw, [13~14] -T f ), (2) ( Tw ) T f ( ),K [15~16] (2),,Tfoodbotom (x,y,z)= 1 Tban(x,y,z)=243K 1.1 (3) 1 2,, Ts[S(t),t]=Tl[S(t),t]=T p, (3) KK25F55TI ( 400 mm 400mm 130mm) 100mm 100mm 70mm 1 1.3 Figure1 Thefreezerandputfood 100 mm 100 mm 70mm, CAD, Gambit Fluent15.0, Fluent15.0, k-ε,, 2 (cm), Figure2 Foodputthepositionofthemainview 10-6,, Z, -9.81m/s 2 1.2, ( ) Fluent15.0 1 5s, ;2,, ;3 18060s -18,, ;4 3 ( 1050kg/m 3 );5 118 λs Ts Tl x =λl x +h ρ ( 4) Ts Tl T p λs,w/(m K); λl,w/(m K); h,kj/kg; ρ, kg/m 3 Tfood(x,y,z)=T0 =278.15 K,, ;6 XOY 5 ( 4), X 0.00,0.02, 0.04,-0.01,-0.03m
第 ３３ 卷第 ７ 期 唐 婉等 牛肉冻结过程中模拟及热值传递理论分析 由图 ４ ５ 可知 牛肉底部换热 最 快 温 度 降 低 得 最 快 而 牛肉顶部和侧面降 温 略 慢 这 是 因 为 在 冻 结 过 程 中 食 品 底 部直接与蒸发盘管 接 触 存 在 接 触 导 热 作 用 导 热 的 热 阻 远 小于对流换热的热阻 而且蒸发盘管 的 温 度 要 低 于 冷 冻 室 内 部环境的温度 所以食品底部的温度下降较快 ２ 牛肉冻结过程中试验研究与结果分析 ２ １ 试验研究 选 取新鲜牛肉 准确切取 １００ｍｍ １００ｍｍ ７０ｍｍ 规 图 ３ 牛肉体最高温度分布曲线 则的长方体形状 用标定好的美国 ＯＭＥＧＡ 四氟测温线 ＴＴ ３ Ｃ ｈｈ ｍｐ ｄ ｂ ｏｎ ｖ ｇ ｇｈ Ｔ ３６ 型 热 电 偶 温 度 探 头 固 定 好 测 点 位 置 置 于 恒 温 恒 湿 箱 图 ４ 不同时刻牛肉内部各截面的温度分布云图 ４ Ｄ ｎ ｍｂ ｗ ｈ ｎ ｈ ｏｎ ｍｐ ｄ ｂ ｏｎ ｎ ｈ ｏｄ ｇ 图 ５ 牛肉垂直中心截面位置不同时刻牛温度分布云图 ５ Ｖ ｎ ｏｎ ｏ ｏｎｂ ｍｐ ｄ ｂ ｏｎ ｎ ｈｄ ｎ ｍ ｏｄ ｇ １１９
2017 7 2d, (5 ) ( 6) 1d,, 30s Fluke2640A Excel 7 Figure7 Foodcentersectionoftheexperimentalvalueof measuringpoints, T2 T3, T2 T1 15mm,T2 25mm,T3,T4, 45 mm,t5 15mm, 7, 6 (cm) -1.0~-2.6,, Figure6 Experimentaltakediagram 5 2.2-29 -30.4 7 T4,CFD, T1, T3, T1, T5, 8(a)~(c) 8 Figure8 Beefexperimentalvalueandsimulationvalueofeachmeasuringpointtemperaturecontrast 120
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