THM-32

Flow exergy snapshot

Availability relative to the dead state.

Reading speed

GoverningFlow exergy snapshot

Governing equation

b=(h-h_0)-T_0(s-s_0)

where

h: h (kJ/kg)
h0: h0 (kJ/kg)
T0: T0 (K)
s: s (kJ/(kg·K))
s0: s0 (kJ/(kg·K))
b: Flow exergy snapshot (kJ/kg)

Lecture brief

Historical brief

Carnot (1824), Clausius entropy, the first law and later van der Waals and Gibbs potentials turned heat into a state science. The sheets compute work, efficiency and vapour pressure. This sheet (THM-32 — Flow exergy snapshot) is the form associated with Flow exergy snapshot. Working symbols: $h$ , $h0$ , $T0$ , $s$ , $s0$ $\rightarrow$ $b$ . Availability relative to the dead state. Pedagogical SI sheet with a live model and a swept parameter.

Purpose

Purpose: compute

b

from

h

h0

T0

s

s0

in Thermodynamics via

b=(h-h_0)-T_0(s-s_0)

Availability relative to the dead state. Use it when a real thermodynamics question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

h = 400.000\,\mathrm{kJ/kg}

h0 = 300.000\,\mathrm{kJ/kg}

T0 = 298.000\,\mathrm{K}

s = 1.600\,\mathrm{kJ/(kg·K)}

s0 = 1.200\,\mathrm{kJ/(kg·K)}

, the governing relation

b=(h-h_0)-T_0(s-s_0)

yields

b = -19.200\,\mathrm{kJ/kg}

. One governing identity, SI units, a single sweep on the sheet. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

h h400 kJ/kgh0 h0300 kJ/kgT0 T0298 Ks s1.6 kJ/(kg·K)s0 s01.2 kJ/(kg·K)

Outputs

Flow exergy snapshot b-19.200 kJ/kg

Reading speed

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Narration of this film

One governing identity, SI units, a single sweep on the sheet.

Availability relative to the dead state. Pedagogical SI sheet with a live model and a swept parameter.

Reading speed

Watch on YouTube