Half a croissant, on a plate, with a sign in front of it saying '50c'
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In-flight Meals Warmer

Engine exhaust heat recovery
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Self explanatory.

However, in brief, the proposed system will consist of heat exchanger & necessary controls to maintain the meals at the desired temperature.

The weight of heat exchanger will be compensated by removal of existing electric (?) oven.

vedarshi, May 19 2008

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       It's probably a microwave.
phoenix, May 19 2008
  

       [phoenix] even if a microwave, it would require power to operate. the proposed idea is to use engine waste heat and eliminate the use of microwave or other type of oven.   

       moreover, HX system would be highly efficient compared to existing device.
vedarshi, May 19 2008
  

       A lot of airlines do not serve meals anymore...
xandram, May 19 2008
  

       Are you saving power or weight? A microwave is small, light and while it uses some power, I'd guess the load is negligible. Adding the components necessary to tap this waste heat would certainly be heavier and require their own periodic inspection.
phoenix, May 19 2008
  

       The heat exchanger sounds too complicated. Just have a long gripper arm that holds the foil-packed meal behind the engine for a few seconds.
Srimech, May 19 2008
  

       [phoenix] 1) i would be saving power.   

       2) if you feel that due to negligible(?) load, there is no need to replace microwave with HX, there is no point in arguing further.   

       3) i mentioned about the 'weight' to avoid associated arguments that would have come up. i am quite sure light weight, maintenance/ inspection free HX can be designed (if HXs can work in extremely corrosive/erosive environment e.g. in a chemical plant, i don't see any reason why a much simpler system can't be designed for aircraft).   

       [srimech] the HX was proposed after duly considering something like gripper arm that you have suggested (which would involve design complications). HX will be a passive system.
vedarshi, May 20 2008
  

       The cabin area of many passenger aircraft is modular -- galleys, seats, most everything, can be added or removed. Some airlines change cabin configurations for seasonal routes. It's much safer and simpler to connect to an existing power bus, than to hook up to a duct which would need outlets for various optional oven locations.   

       Aircraft ovens are operated for a few minutes each flight. Any fuel savings would be greatly offset by having to route heated engine air into this oven-hot ductwork throughout the cabin.   

       When asking the question "why aren't aircraft built with X?", something that might make sense at first has probably been reviewed by many engineers. Often, the current system or device is the safest and most reliable choice allowed by regulations. But it sometimes makes for an interesting discussion.
Amos Kito, May 20 2008
  

       [Amos Kito] In whichever flight I have travelled, I have found the meals heating system either near front door or in the rearmost area. The passive HXs will supply heat at only these locations; there is no need for ducting to provide warming facility to individual passengers.
vedarshi, May 20 2008
  

       Remember that airplanes are designed "fail safe". A microwave is a fail safe device. An engine powered HX is NOT as fail safe. They use microwaves for this reason and also because they heat only the food and not the container in which it resides reducing the chance of accidental scalding and speeding the rate at which food can be served. The savings in energy relative to the total output of a jet airplane and its efficiency relative to other modes of transportation makes this idea comical.
WcW, May 20 2008
  

       [WCW] //They use microwaves for this reason and also because they heat only the food and not the container in which it resides reducing the chance of accidental scalding and speeding the rate at which food can be served//   

       I accept it as a valid argument.   

       //The savings in energy relative to the total output of a jet airplane and its efficiency relative to other modes of transportation makes this idea comical//   

       I disagree with this argument. Generation of electricity to run microwave involves inefficiency of prime mover, generator, electricity storage/transmission system. The waste heat recovery HX system would have much higher efficiency/effectiveness.
vedarshi, May 21 2008
  

       If you already offer 120v wired into every single seat this seems like a simple matter of plug-and-play. In reality I suspect that microwaving is the best way to reheat airplane food and thus proposing another way of heating it would require a new menu and prep situation.
WcW, May 21 2008
  
      
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