Functional Requirements

This section provides the functional requirements, the tasks and behaviours that the software is expected to complete.

Input-Values: Input the values from Tab:ReqInputs, which define the tank parameters, material properties, and initial conditions.

Find-Mass: Use the inputs in FR:Input-Values to find the masses needed for IM:eBalanceOnWtr, IM:eBalanceOnPCM, IM:heatEInWtr, and IM:heatEInPCM, using DD:waterMass, DD:waterVolume_pcm, and DD:tankVolume.

Check-Input-with-Physical_Constraints: Verify that the inputs satisfy the required physical constraints.

Output-Input-Derived-Values: Output the input values and derived values in the following list: the values (from FR:Input-Values), the masses (from FR:Find-Mass), ${τ_{\text{W}}}$ (from DD:balanceDecayRate), $η$ (from DD:balanceDecayTime), ${{τ_{\text{P}}}^{\text{S}}}$ (from DD:balanceSolidPCM), and ${{τ_{\text{P}}}^{\text{L}}}$ (from DD:balanceLiquidPCM).

Calculate-Values: Calculate the following values: ${T_{\text{W}}}$ ( $t$ ) (from IM:eBalanceOnWtr), ${T_{\text{P}}}$ ( $t$ ) (from IM:eBalanceOnPCM), ${E_{\text{W}}}$ ( $t$ ) (from IM:heatEInWtr), and ${E_{\text{P}}}$ ( $t$ ) (from IM:heatEInPCM).

Verify-Energy-Output-Follow-Conservation-of-Energy: Verify that the energy outputs ( ${E_{\text{W}}}$ ( $t$ ) and ${E_{\text{P}}}$ ( $t$ )) follow the law of conservation of energy, as outlined in Properties of a Correct Solution, with relative error no greater than ${C_{\text{tol}}}$ .

Calculate-PCM-Melt-Begin-Time: Calculate and output the time at which the PCM begins to melt ${{t_{\text{melt}}}^{\text{init}}}$ (from IM:eBalanceOnPCM).

Calculate-PCM-Melt-End-Time: Calculate and output the time at which the PCM stops melting ${{t_{\text{melt}}}^{\text{final}}}$ (from IM:eBalanceOnPCM).

Output-Values: Output ${T_{\text{W}}}$ ( $t$ ) (from IM:eBalanceOnWtr), ${T_{\text{P}}}$ ( $t$ ) (from IM:eBalanceOnPCM), ${E_{\text{W}}}$ ( $t$ ) (from IM:heatEInWtr), and ${E_{\text{P}}}$ ( $t$ ) (from IM:heatEInPCM).

Symbol	Description	Units
${A_{\text{C}}}$	Heating coil surface area	${\text{m}^{2}}$
${A_{\text{P}}}$	Phase change material surface area	${\text{m}^{2}}$
${A_{\text{tol}}}$	Absolute tolerance	–
${{C_{\text{P}}}^{\text{L}}}$	Specific heat capacity of PCM as a liquid	$\frac{\text{J}}{\text{kg}{}^{\circ}\text{C}}$
${{C_{\text{P}}}^{\text{S}}}$	Specific heat capacity of PCM as a solid	$\frac{\text{J}}{\text{kg}{}^{\circ}\text{C}}$
${C_{\text{W}}}$	Specific heat capacity of water	$\frac{\text{J}}{\text{kg}{}^{\circ}\text{C}}$
$D$	Diameter of tank	${\text{m}}$
${H_{\text{f}}}$	Specific latent heat of fusion	$\frac{\text{J}}{\text{kg}}$
${h_{\text{C}}}$	Convective heat transfer coefficient between coil and water	$\frac{\text{W}}{\text{m}^{2}{}^{\circ}\text{C}}$
${h_{\text{P}}}$	Convective heat transfer coefficient between PCM and water	$\frac{\text{W}}{\text{m}^{2}{}^{\circ}\text{C}}$
$L$	Length of tank	${\text{m}}$
${R_{\text{tol}}}$	Relative tolerance	–
${T_{\text{C}}}$	Temperature of the heating coil	${{}^{\circ}\text{C}}$
${T_{\text{init}}}$	Initial temperature	${{}^{\circ}\text{C}}$
${{T_{\text{melt}}}^{\text{P}}}$	Melting point temperature for PCM	${{}^{\circ}\text{C}}$
${t_{\text{final}}}$	Final time	${\text{s}}$
${t_{\text{step}}}$	Time step for simulation	${\text{s}}$
${V_{\text{P}}}$	Volume of PCM	${\text{m}^{3}}$
${ρ_{\text{P}}}$	Density of PCM	$\frac{\text{kg}}{\text{m}^{3}}$
${ρ_{\text{W}}}$	Density of water	$\frac{\text{kg}}{\text{m}^{3}}$

Required Inputs

Software Requirements Specification for Solar Water Heating Systems Incorporating PCM

Functional Requirements