1 / 40

Preventing Thermal Runaways of LENR Reactors

Preventing Thermal Runaways of LENR Reactors. Jacques Ruer sfsnmc. Temperature activated reactions. Several authors report that the LENR power measured in the experiments increases with the temperature .

rwest
Download Presentation

Preventing Thermal Runaways of LENR Reactors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Preventing Thermal Runaways of LENR Reactors Jacques Ruer sfsnmc

  2. Temperature activated reactions • Severalauthors report that the LENR power measured in the experimentsincreaseswith the temperature. • Arrhenius’ theoryteachesthat the rate of a process, for instance heat-producingreactions, is a function of an activation energyE and the temperatureT : w= A.exp(-E/kT) • where: • wis the heat-production power (W.m-3) • A the pre-exponentialfactor • E the activation energy • k the Boltzmann’sconstant • Tthe absolutetemperature of the reactive medium.

  3. How to control such a reactor ? • The stability of T activated reactors is frequently discussed with a diagram similar to this one • Such diagrams refer to the operation of batch reactors in the chemical industry Storms – How Basic Behavior of LENR can Guide. A Search for an Explanation, JCMNS, 20 (2016), 105-143

  4. Batch reactor • Largelyused for synthesis of manydifferentchemicalproducts • The reactorisloadedwith the reactants, the reactioniscompleted, the productisunloaded

  5. Batch reactor • Endothermicreaction: Reactioncontrolled by heating, no problem • Exothermicreaction: If temperaturegoes out of control, thingsmay go wrong

  6. Batch reactor control • Temperature is controlled by the combination of wall cooling and stirring to enhance heat exchange between charge and wall

  7. Batch reactor control Point of non return Basics: • Temperature must be maintained below the point of non return at any time Cooling power Heat flow Reactionheat power Temperature

  8. How to start the reaction ? • After loading, the temperature is low Initial temperature Heat flow Temperature

  9. How to start the reaction ? • As long as the temperature is low, the reaction has no reason to start

  10. How to start the reaction ? • To start the reaction you have to tease the dragon’s tail

  11. How to start the reaction ? • Start-up by heating Heatingfluidtemperature Heat flow Initial charge temperature Heatingwith hot water or steam Temperature

  12. How to control the reaction ? • Taming the dragon with water cooling

  13. How to control the reaction ? • Reaction rate is controlled by adjusting the cooling Heatisremovedatthistemperature Heat flow Operating point Temperature

  14. Loss of control • If cooling is not sufficient the temperature goes out of control Heat flow Temperature

  15. Loss of control RUNAWAY !

  16. Role of thermal inertia • Example: Polystyrenepolymerization • Reactorloadedwithreactantsat the beginning of the operation « All on board » • T rises slowly because of thermal inertia • T decays when reactants become exhausted T max (styrenevapor pressure)

  17. Control by thermal inertia • Exhausting the dragon

  18. Control of reactants input • Example: Synthesis of nitroglycerin • Acidisaddedslowly to the charge T max (explosion safetymargin) • Reaction start: 22°C • If T> 30°C, the charge is dumped out in water

  19. Control of reactants input • Feeding the dragon slowly

  20. Control with a large heat exchange Heating power P • Reaction is controlled by adjusting the coolant temperature Cooling power h.DT Heatisrecoveredatthistemperature Heat flow Operating point DT Temperature

  21. Stability dP/dT > hcooling EXTINCTION Heat flow Temperature

  22. Stability dP/dT > hcooling UNSTABLE RUNAWAY Heat flow Temperature

  23. Stability dP/dT > hcooling dP/dT < hcooling SELF HEATING UNSTABLE Heat flow Heat flow Temperature Temperature

  24. Stability The reactor is stable if hcooling > dP/dTheating dP/dT > hcooling dP/dT < hcooling STABLE UNSTABLE SELF COOLING Heat flow Heat flow Temperature Temperature

  25. Differences between LENR Reactorand Batch Reactor • LENR : Reaction is continuous • Thermal inertia can only help during transients • Activation energy may be high, so that temperature sensitivity may be high • Heat is preferably recovered at high temperature (for conversion efficiency) • Reference to the thermal behavior of batch reactors is inappropriate

  26. Continuous reactors • In the chemical industry some reactors are designed for continuous operation • Example : Production of synthetic fuels by the Fisher-Tropsch process

  27. Fischer-Tropsch Process • Production of synthetic fuels from CO+H2 gas • Reaction (synthesis of alkanes - simplified) : nCO + (2n+1)H2 ------> CnH2n+2 + nH2O DH =-n.165kJ • Yields a blend of hydrocarbons : methane, gasoline, distillates, waxes, etc. • The proportions depend on the type of catalyst (Fe-Co-Ni) and the process conditions (pressure and temperature)

  28. Fisher-Tropsch Process Temperature is an essential parameter • Example of the proportions of methane and gasoline in the product output After: Cailian Ma, , Yilong Chen, Jiangang Chen - Surfactant-Assisted Preparation of FeCu Catalyst for Fischer-Tropsch Synthesis

  29. Fisher-Tropsch Reactors • FT reactors must be designed to allow an efficient control of the heat flow: • The reaction is highly exothermic • The temperature must be maintained in a narrow range to produce the valuable hydrocarbons

  30. Fisher-Tropsch Reactors • Example: • Multitube reactor ARGE design • 2000 tubes dia 50mm • Main features: • High heat transfer capability • Heat removal by a hot fluid (steam)

  31. Fisher-Tropsch Reactors • Some concepts utilize microchannels technology to ensure a very high heat exchange and a uniform temperature in the reactor

  32. Multitube design Multitube design is already used in the nuclear industry to guarantee the high heat flux required The challenge is to limit the surface temperature of the tubes and avoid water splitting Nuclear fuel assembly for a PWR

  33. Potential design LENR systems • LENR reactors may be controlled via the cooling fluid temperature • Additional control possible for some types via gas pressure, electrical excitation input, etc. • If the reactor is sensitive to the temperature, a high heat exchange design is compulsory

  34. Plate and tubular types LENR reactors The cells are immerged in a forced flow of cooling fluid Condition for stability ?

  35. Plate and tubular types LENR reactors Hypotheses: LENR specific power : w (W.m-3) Arrhenius’ law activation energy : E (J) Operating temperature : T (K) Heat exchange coefficient : h (W.m-2.K-1)

  36. Plate and tubular types LENR reactors Conditions for stability h > Ewt/kT2 h > ½ Ewr/kT2 Hypotheses: LENR specific power : w (W.m-3) Arrhenius’ law activation energy : E (J) Operating temperature : T (K) Heat exchange coefficient : h (W.m-2.K-1)

  37. LENR Reactor Cooling • Cooling by forced liquid flow and/or boiling liquid • Cooling by forced organized gas flow

  38. Cooling and conversion

  39. Please do no longer refer to suchdiagrams for continous LENR reactors

  40. Thank you for your attention

More Related