Legacy · Thermal validation

Cylindrical shaft

One isothermal calibration, three placement temperatures. What changes with T0T_0 is the time parameter of the particular curve and TmaxT_{\max}. The regressed amplitude stays at 50∘C50\,^{\circ}\mathrm{C}.

Paper: Analytical and numerical validation of the thermochemical problem of early-age concrete · DOI 10.70271/rirc.v1n2a008

Input data

Item Value
Radius r=0.5mr=0.5\,\mathrm{m} (FEM domain LX=5mL_X=5\,\mathrm{m})
TmaxT_{\max} point axis (0,0)(0,0)
Q(teq)Q(t_{eq}), one Hill term ΔT=50∘C\Delta T=50\,^{\circ}\mathrm{C}, a1=40.10873ha_1=40.10873\,\mathrm{h}, c1=1.54782c_1=1.54782
Ea/RE_a/R in the model 4000K4000\,\mathrm{K}
TrefT_{\mathrm{ref}} 20∘C20\,^{\circ}\mathrm{C}
T0T_0 2020, 3030 or 40∘C40\,^{\circ}\mathrm{C}
T∞T_{\infty} on the cold faces 20∘C20\,^{\circ}\mathrm{C}
Concrete k=9kJ/(m⋅h⋅∘C)k=9\,\mathrm{kJ/(m\cdot h\cdot^{\circ}C)}; ρ=2400kg/m3\rho=2400\,\mathrm{kg/m^3}; ce=0.75kJ/(kg⋅∘C)c_e=0.75\,\mathrm{kJ/(kg\cdot^{\circ}C)}; h2=0.005m2/hh^{2}=0.005\,\mathrm{m^2/h}
Horizon tf=480ht_f=480\,\mathrm{h}
CC in the QQ column 300kg/m3300\,\mathrm{kg/m^3}

The report states the source as a rise ΔTQ\Delta T^{Q}, not as a cement content. Q_kJ_kg uses C=300kg/m3C=300\,\mathrm{kg/m^3}, the interconversion consumption, only to close the unit. A code that integrates in °C uses ΔTQ=QC/(ρce)\Delta T^{Q}=Q\,C/(\rho c_e).

The analytical route regresses the particular curve with Ea/R=0E_a/R=0. The input Q(teq)Q(t_{eq}) is not recalibrated.

Reference result

From the report. Regressed ΔT\Delta T stays at 50.00∘C50.00\,^{\circ}\mathrm{C} (deviation under 0.01%0.01\%). β=1.549\beta=1.549.

T0T_0 (°C) τ\tau (h) RMSE of T(t)T(t) (°C) TmaxT_{\max} FEM / analytical (°C)
20 23.63 0.012 43.3 / 43.3
30 15.38 0.090 52.4 / 52.6
40 10.35 0.166 62.8 / 63.2

The largest error in the geometry × T0T_0 matrix is this shaft at 40∘C40\,^{\circ}\mathrm{C}. On the series of this page the FEM peaks are 43.31∘C43.31\,^{\circ}\mathrm{C} (42.07h42.07\,\mathrm{h}), 52.39∘C52.39\,^{\circ}\mathrm{C} (27.28h27.28\,\mathrm{h}) and 62.85∘C62.85\,^{\circ}\mathrm{C} (18.48h18.48\,\mathrm{h}).

The shaft FEM file did not store the generation column. In the particular series, Q_kJ_kg was rebuilt from the regressed Hill law (ΔT\Delta T, τ\tau, β\beta) of each placement.

Series t × Tmax × teq × Q(t)

No suffix: Tmax_C is the FEM axis temperature, teq_h uses Ea/R=4000KE_a/R=4000\,\mathrm{K} and Tref=20∘CT_{\mathrm{ref}}=20\,^{\circ}\mathrm{C}, Q_kJ_kg is the 50∘C50\,^{\circ}\mathrm{C} isothermal calibration at that teqt_{eq}.

Suffix _particular: teq_h =t=t and Q_kJ_kg is the particular curve (Ea/R=0E_a/R=0) used by the analytical solution.

Report figures

T(t) panel Contours at t of Tmax Section cut Shaft, T0 = 20 °C Shaft, T0 = 30 °C Shaft, T0 = 40 °C