Thermomagnetic fluid engine

Matrix context

D = disequilibrium row · C = coupling family column. A cell reads the state of the atlas for that pair.

D.01 × C.06 · Temperature gradient × Thermomagneticfamily: ThermomagneticD.01 × C.24 · Temperature gradient × Turbomachineryfamily: Turbomachinery

Measured or reported performance

1. rotor angular velocity≈ 2.1 rad/min peakdevice2009
   kerosene-based temperature-sensitive magnetic fluid, permanent NdFeB magnet, rotor in the circulating fluid; speed rises with heat input and with a colder heat sink — no shaft power reported; a miniature demonstration of the mechanism
   refs [3]

Typed bounds on this route

Every limit the atlas holds for this route, as constraint records: reached through bounded_by claims on the route's own entities. Hard bounds (an upper bound or a formula) decide the thermodynamic-bound check above; benchmarks, constitutive relations and resource limits are listed and never decisive. No prose limit exists anywhere (pass 42).

• Carnot limit · formula-bound · hard, applies to this route
  η ≤ 1 − T_c/T_h for any heat engine between reservoirs at T_h and T_c
• Betz limit · upper-bound · hard, filtered out by its applicability
  C_p ≤ 16/27 ≈ 59.3% of the kinetic power through the rotor disc

Steps

1. 01
   Temperature gradient —drives→ Thermomagnetic convectionestablishedclaim record

   thermal → kinetic · loss to thermal

   • a ferrofluid whose magnetisation decreases with temperature, in a non-uniform magnetic field aligned with the temperature gradient

   liquid · magnetic field required · temperature gradient required

   refs [1] [2]
2. 02
   Thermomagnetic convection —produces→ Fluid flowestablishedclaim record

   kinetic → kinetic

   The circulating flow carries a directed momentum flux that can load a blade: Zhou et al. 2009 drove a rotor with it (recorded as pathway:thermomagnetic-fluid-engine).

   refs [1] [3]
3. 03
   Fluid flow —drives→ Aerodynamic and hydrodynamic liftestablishedclaim record

   kinetic → mechanical · loss to thermal

   • a rotor or vane in the produced stream at a working angle of attack; the driven flow must carry a directed momentum flux for a blade to load

   bulk flow required

   refs [4] [5]
4. 04
   Aerodynamic and hydrodynamic lift —produces→ Mechanical motionestablishedclaim record

   mechanical → mechanical

   refs [5]
5. 05
   Mechanical motion —converts into→ Mechanical workestablishedclaim record

   mechanical → mechanical · loss to thermal

   refs [6]

Evidence for the complete composition · 1

1. [3]
   L. Zhou et al.. A new miniaturized engine based on thermomagnetic effect of magnetic fluids (2009)

   Frontiers of Energy and Power Engineering in China 3, 160–166 · doi:10.1007/s11708-009-0018-9 · record

Evidence for the constituent relations · 6

1. [1]
   R. E. Rosensweig. Ferrohydrodynamics (1985)

   Cambridge University Press · book, no DOI · record
2. [2]
   S. A. Suslov. Peculiarities of Convective Heat and Mass Transfer in Magnetic Nanofluids (2023)

   ASME Journal of Heat and Mass Transfer 145(3), 030801 (online December 2022) · doi:10.1115/1.4055343 · crossref ✓ 2026-09-20 · record
3. [3]
   L. Zhou et al.. A new miniaturized engine based on thermomagnetic effect of magnetic fluids (2009)

   Frontiers of Energy and Power Engineering in China 3, 160–166 · doi:10.1007/s11708-009-0018-9 · record
4. [4]
   A. Betz. Das Maximum der theoretisch möglichen Ausnützung des Windes durch Windmotoren (1920)

   Zeitschrift für das gesamte Turbinenwesen 26, 307–309 · paper, no DOI · record
5. [5]
   S. L. Dixon, C. A. Hall. Fluid Mechanics and Thermodynamics of Turbomachinery (7th ed.) (2014)

   Butterworth-Heinemann · doi:10.1016/C2011-0-05059-7 · crossref ✓ 2026-09-19 · record
6. [6]
   A. Bejan. Advanced Engineering Thermodynamics (4th ed.) (2016)

   Wiley · doi:10.1002/9781119245964 · crossref ✓ 2026-09-19 · record