ERROR ANALYSIS OF THE HEAT PULSE METHOD FOR MEASURING SOIL VOLUMETRIC HEAT-CAPACITY
ERROR ANALYSIS OF THE HEAT PULSE METHOD FOR MEASURING SOIL VOLUMETRIC HEAT-CAPACITY
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DOI：
10.2136/sssaj1993.03615995005700060008x
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发表时间：
1993-11-01
影响因子：
2.9
通讯作者：
BRISTOW, KL
中科院分区：
文献类型：
--
作者：
KLUITENBERG, GJ;HAM, JM;BRISTOW, KL
最近开发的热脉冲方法可以快速，自动测量土壤的体积热容（ρ c）。的rho c的估计是通过使用一个模型的热传导远离瞬时加热的无限线源（IHILS）。这项研究的目的是通过将IHILS模型与其他三个模型进行比较来检查使用IHILS理论时可能存在的错误，这些模型充分考虑了热脉冲装置的以下特征：有限的探针长度、圆柱形加热器几何形状和短时间（非瞬时）加热。对于典型的探头几何形状和加热时间，从IHILS理论获得的rho c估计值在使用更严格的模型获得的估计值的1%以内。IHILS模式中最显著的误差来自于用瞬时加热近似短时加热。一个广义的误差分析，允许直接图形估计不同的探头几何形状，不同的加热时间，和不同的土壤热性能的错误。一阶误差分析也用于检查由于探针间距（r）、温度最大值（T-m）和热输入（q）的误差而导致的pr的潜在误差，这些测量量用于IHILS模型中以估计rho c。测量q和T-m的相对误差为1%时，ρ c的相对误差为1%，而r的相对误差为1%时，误差为2%。r和T-m的测量误差限制了该方法可达到的精度。
A recently developed heat pulse method allows rapid, automated measurements of the volumetric heat capacity (rho c) of soil. Estimation of rho c is accomplished by using a model for the conduction of heat away from an instantaneously heated infinite line source (IHILS). This study was conducted to examine possible errors in the use of the IHILS theory by comparing the IHILS model with three other models that account far the following characteristics of the heat pulse apparatus: finite probe length, cylindrical heater geometry, and short-duration (noninstantaneous) heating. For typical probe geometry and heating times, estimates of rho c obtained from the IHILS theory were within 1% of the estimates obtained by using the more rigorous models. The most significant error resulted from approximating short-duration heating with instantaneous heating in the IHILS model. A generalized error analysis is presented that permits direct graphical estimation of errors for different probe geometries, different heating times, and different soil thermal properties. First-order error analysis was also used to examine potential error in pr as a result of errors in probe spacing (r), temperature maximum (T-m), and heat input (q), the measured quantities that are used in the IHILS model to estimate rho c. Relative errors of 1% in measuring q and T-m lead to relative errors of 1% in rho c, whereas a relative error of 1% in r resulted in a 2% error. Measurement error in r and T-m limits the precision achievable with this method.