Notations and Units

Table 1. Symbols and Units

Symbol

Quantity

Unit

\(c_{\mathrm{m}}\)

specific heat capacity of dry material

\(\mathrm{J} /(\mathrm{kg} \cdot \mathrm{K})\)

\(c_{\mathrm{w}}\)

specific heat capacity of liquid water

\(\mathrm{J} /(\mathrm{kg} \cdot \mathrm{K})\)

\(D_{\mathrm{w}}\)

moisture diffusivity

\(\mathrm{m}^{2} / \mathrm{s}\)

\(E_{\mathrm{sol}}\)

total flux density of incident solar radiation

\(\mathrm{W} / \mathrm{m}^{2}\)

\(g\)

density of moisture flow rate

\(\mathrm{kg} /\left(\mathrm{m}^{2} \cdot \mathrm{s}\right)\)

\(g_{\mathrm{p}}\)

density of moisture flow rate of available water from precipitation

\(\mathrm{kg} /\left(\mathrm{m}^{2} \cdot \mathrm{s}\right)\)

\(g_{\mathrm{v}}\)

density of water vapour flow rate

\(\mathrm{kg} /\left(\mathrm{m}^{2} \cdot \mathrm{s}\right) \)

\(g_{\mathrm{w}}\)

density of liquid water flow rate

\(\mathrm{kg} /\left(\mathrm{m}^{2} \cdot \mathrm{s}\right) \)

\(g_{\mathrm{w}, \max }\)

density of water flow rate which can be absorbed at the surface of a material

\(\mathrm {kg} /\left(\mathrm{m}^{2} \cdot \mathrm{s}\right)\)

\(h\)

surface heat transfer coefficient

\(\mathrm{W} /\left(\mathrm{m}^{2} \cdot \mathrm{K}\right)\)

\(h_{\mathrm{c}}\)

convective heat transfer coefficient

\(\mathrm{W} /\left(\mathrm{m}^{2} \cdot \mathrm{K}\right)\)

\(h_{\mathrm{e}}\)

specific latent enthalpy of evaporation or condensation

\(\mathrm{J} / \mathrm{kg}\)

\(h_{\mathrm{r}}\)

radiative heat transfer coefficient

\(\mathrm{W} /\left(\mathrm{m}^{2} \cdot \mathrm{K}\right)\)

\(K\)

liquid conductivity

\(\mathrm{s} / \mathrm{m}\)

\(p_{\mathrm{a}}\)

ambient atmospheric pressure

\(\mathrm{Pa}\)

\(p_{\text {suc }}\)

suction pressure

\(\mathrm{Pa}\)

\(p_{\mathrm{v}}\)

partial water vapour pressure

\(\mathrm{Pa}\)

\(p_{\mathrm{v}, \mathrm{a}}\)

partial water vapour pressure in the air

\(\mathrm{Pa}\)

\(p_{\mathrm{v}, \mathrm{s}}\)

partial water vapour pressure at a surface

\(\mathrm{Pa}\)

\(p_{\mathrm{v}, \mathrm{sat}}\)

saturated water vapour pressure

\(\mathrm{Pa}\)

\(p_{\mathrm{w}}\)

water pressure inside pores

\(\mathrm{Pa}\)

\(q\)

density of heat flow rate

\(\mathrm{W} / \mathrm{m}^{2}\)

\(q_{\text {lat }}\)

density of latent heat flow rate

\(\mathrm{W} / \mathrm{m}^{2}\)

\(q_{\text {sens }}\)

density of sensible heat flow rate

\(\mathrm{W} / \mathrm{m}^{2}\)

\(R_{\mathrm{w}}\)

liquid moisture flow resistance of interface

\(\mathrm{m} / \mathrm{s}\)

\(R_{\mathrm{H} 2 \mathrm{O}}\)

gas constant of water vapour

\(\mathrm{J} /(\mathrm{kg} \cdot \mathrm{K})\)

\(s_{\mathrm{d}, \mathrm{s}}\)

equivalent vapour diffusion thickness of a surface layer

\(\mathrm{m}\)

\(T\)

thermodynamic temperature

\(\mathrm{K}\)

\(T_{\mathrm{a}}\)

air temperature of the surrounding environment

\(\mathrm{K}\)

\(T_{\mathrm{eq}}\)

equivalent temperature of the surrounding environment

\(\mathrm{K}\)

\(T_{\mathrm{r}}\)

mean radiant temperature of the surrounding environment

\(\mathrm{K}\)

\(T_{\text {surf }}\)

surface temperature

\(\mathrm{K}\)

\(t\)

time

\(\mathrm{s}\)

\(v\)

wind speed

\(\mathrm{m} / \mathrm{s}\)

\(w\)

moisture content

\(\mathrm{kg} / \mathrm{m}^{3}\)

\(\alpha_{\mathrm{sol}}\)

distance

\(\mathrm{m}\)

\(\delta_{0}\)

solar absorptance

\(\mathrm{kg} /(\mathrm{m} \cdot \mathrm{s} \cdot \mathrm{Pa})\)

\(\delta_{\mathrm{p}}\)

vapour permeability of still air

\(\mathrm{kg} /(\mathrm{m} \cdot \mathrm{s} \cdot \mathrm{Pa})\)

\(\varepsilon\)

vapour permeability of material

\(-\)

\(\lambda\)

longwave emissivity of the external surface

\(\mathrm{W} / \mathrm{m} \cdot \mathrm{K})\)

\(\varphi\)

thermal conductivity

\(-\)

\(\mu\)

relative humidity

\(\mathrm{kg} / \mathrm{m}^{3}\)

\(\rho_{\mathrm{a}}\)

diffusion resistance factor

\(\mathrm{kg} / \mathrm{m}^{3}\)

\(\rho_{\mathrm{m}}\)

density of air

\(\mathrm{kg} / \mathrm{m}^{3}\)

\(\sigma_{\mathrm{w}}\)

density of solid matrix

\(\mathrm{density}\) of liquid water

\(\rho_{\mathrm{w}}\)

density of liquid water

\(\mathrm{kg} / \mathrm{m}^{3}\)

\(\sigma_{\mathrm{s}}\)

Stefan-Boltzmann constant

\(\mathrm{W} /\left(\mathrm{m}^{2} \cdot \mathrm{K}^{4}\right)\)