The thermal conductivity of water

Martin, Leslie Harold; Lang, Ken-jen

doi:10.1088/0959-5309/45/4/304

Cited by 15 publications

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“…If the volumetric heat capacity ( ρc , J m −3 K −1 ) of the sapwood is known, its water content (MC, kg water (kg dry weight) –1 ) can be determined directly (Swanson, 1983): ( c w and c dw , heat capacities of water (4186 J kg −1 K −1 ; Martin & Lang, 1933) and dry wood (1200 J kg −1 K −1 ; Edwards & Warwick, 1984), respectively; ρ d , dry wood density (kg m −3 ), which can be measured once by sampling a wood core).…”

Section: Methodsmentioning

confidence: 99%

“…( T , temperature ( K ); t , time (s); P , power input (W m −3 ); ρ , density; c , specific heat capacity; , thermal conductivity vector, consisting of radial ( K rad ), axial ( K ax ) and tangential ( K tg ) conductivity, of the medium in which the measurements are conducted). For the immobilized water, values of 1000 kg m −3 and 4186 J kg −1 K −1 were taken for ρ and c , and, for K ax , K tg and K rad , a value of 0.61 W m −1 K −1 was applied (Martin & Lang, 1933). For the measurement and heater needles, the properties of steel were chosen for implementation in the model ( ρ = 7850 kg m −3 , c = 475 J kg −1 K −1 , K = 44.5 W m −1 K −1 ).…”

Section: Methodsmentioning

confidence: 99%

“…(c w and c dw , heat capacities of water (4186 J kg )1 K )1 ; Martin & Lang, 1933) and dry wood (1200 J kg )1 K )1 ; Edwards & Warwick, 1984), respectively; q d , dry wood density (kg m )3 ), which can be measured once by sampling a wood core).…”

Section: Water Contentmentioning

confidence: 99%

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Sapflow+: a four‐needle heat‐pulse sap flow sensor enabling nonempirical sap flux density and water content measurements

Vandegehuchte

Steppe

2012

New Phytologist

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Summary• To our knowledge, to date, no nonempirical method exists to measure reverse, low or high sap flux density. Moreover, existing sap flow methods require destructive wood core measurements to determine sapwood water content, necessary to convert heat velocity to sap flux density, not only damaging the tree, but also neglecting seasonal variability in sapwood water content.• Here, we present a nonempirical heat-pulse-based method and coupled sensor which measure temperature changes around a linear heater in both axial and tangential directions after application of a heat pulse. By fitting the correct heat conduction-convection equation to the measured temperature profiles, the heat velocity and water content of the sapwood can be determined.• An identifiability analysis and validation tests on artificial and real stem segments of European beech (Fagus sylvatica L.) confirm the applicability of the method, leading to accurate determinations of heat velocity, water content and hence sap flux density.• The proposed method enables sap flux density measurements to be made across the entire natural occurring sap flux density range of woody plants. Moreover, the water content during low flows can be determined accurately, enabling a correct conversion from heat velocity to sap flux density without destructive core measurements.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Sapflow+: a four‐needle heat‐pulse sap flow sensor enabling nonempirical sap flux density and water content measurements

Vandegehuchte

Steppe

2012

New Phytologist

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“…Operating with a temperature difference of 7°C ., Kaye and Higgins (77) refined the apparatus further, largely accounting for erroneous heat losses by effecting a total energy balance to within 5-10%. Methods similar to this were applied by Martin and Lang (88), Erk and Keller (44), and Kraus (79), while Riedel's modification (103) comprised surrounding the heated plate with two cooling plates, the liquid occupying the intervening spaces.…”

Section: Steady-state Methodsmentioning

confidence: 99%

Methods for Determining Liquid Thermal Conductivities

Tait¹,

Hills²

1964

Ind. Eng. Chem.

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“…The uncertainty in q was derived based on equation ( 1), while the uncertainty in hydraulic diameter was assessed given D h ≡ 2W H/(W + H ). On the other hand, the uncertainty in the thermal conductivity of water, k, was estimated based upon the uncertainty in the measurement of the fluid temperature in conjunction with the variation of k as a function of fluid temperature [40]. Finally, these uncertainties were used to estimate the uncertainty in the bulk heat-transfer coefficient…”

Section: Uncertainty Estimatesmentioning

confidence: 99%

Non-intrusive measurements of transitional and turbulent convective heat transfer in a rectangular microchannel

Natrajan¹,

Christensen²

2011

J. Micromech. Microeng.

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The thermal-transport characteristics of transitional and turbulent flow through smooth- and rough-wall rectangular microchannels (Dh = 600 μm) under constant-heat-flux conditions at three of the four walls were investigated by performing non-intrusive and spatially resolved measurements of fluid temperature via two-color fluorescent thermometry. These measurements, along with bulk pressure-drop measurements, were performed over the Reynolds-number range . The pressure-drop results revealed the onset of transition above for the smooth-wall case, consistent with the onset of transition at the macroscale. However, with increasing surface roughness, deviation from laminar behavior was noted at progressively lower Re which indicates that is a function of roughness. Mean temperature profiles calculated from data sets acquired in the transitional regime for the smooth- and rough-wall cases illustrated deviation from fully developed laminar behavior for . Nevertheless, these profiles still suggest similarities in the transitional pathway of the thermal-transport behavior for the smooth and rough cases save for a relative shift due to the onset of transition at lower Re with increasing surface roughness. Estimates of the bulk Nusselt number indicated enhancement in thermal transport over the smooth-wall case with increasing surface roughness in both the transitional and turbulent regimes, though the smooth-wall data agreed well with macroscale predictions over the range of turbulent Re considered. While the shift in the transitional pathway of the thermal transport behavior toward lower Re accounts for a portion of this enhancement, an increase in turbulent convection with increasing surface roughness might also contribute in this regard.

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The thermal conductivity of water

Cited by 15 publications

References 0 publications

Sapflow+: a four‐needle heat‐pulse sap flow sensor enabling nonempirical sap flux density and water content measurements

Sapflow+: a four‐needle heat‐pulse sap flow sensor enabling nonempirical sap flux density and water content measurements

Methods for Determining Liquid Thermal Conductivities

Non-intrusive measurements of transitional and turbulent convective heat transfer in a rectangular microchannel

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