Heat exchanger configuration for adsorption-based onboard octane on-demand and cetane on-demand

A vehicular fuel system for converting an onboard fuel into octane-rich and cetane-rich components, the fuel system comprising:

• a separation unit comprising at least one adsorbent-based chamber to selectively receive and separate at least a portion of an onboard fuel into an adsorbate as one of an octane-rich fuel component or a cetane-rich fuel component and a remainder as the other of the cetane-rich fuel component and the octane-rich fuel component;
• a product tank for selectively receiving and containing the remainder;
• a fuel supply tank comprising:
• a first compartment for containing the onboard fuel;
• a second compartment disposed within the first compartment and configured to selectively receive a vaporized form of the adsorbate from the separation unit such that at least a portion of the vaporized form of the adsorbate that is present in the second compartment is condensed by an exchange of heat with the onboard fuel that is present in the first compartment;
• and
• a third compartment disposed within the second compartment such that both fluid and heat exchange communication is established between them in order to have the third compartment receive at least a portion of any remaining vaporized adsorbate from the second compartment for at least one of storage and additional condensing;
• and
• fuel conduit configured to deliver at least one of the onboard fuel, the octane-rich fuel component and the cetane-rich fuel component to the combustion chamber from at least one of the separation unit, fuel supply tank and product tank.

A method of operating an internal combustion engine, the method comprising:

• configuring a fuel system to comprise a fuel supply tank with an onboard fuel being disposed in a first compartment of the fuel supply tank, a separation unit and a product tank cooperative with one another through fuel conduit and responsive to directions provided by a controller;
• using the controller to ascertain an operational condition of the engine;
• using the controller to direct the flow of a portion of the onboard fuel to a combustion chamber of the engine without first passing through the separation unit when the engine is in a first operational condition;
• using the controller to direct the flow of a portion of the onboard fuel to the separation unit when the engine is in a second operational condition such that an adsorbate in the form of one of an octane-rich fuel component and a cetane-rich fuel component collects on a surface of at least one chamber of the separation unit, while a remainder of the portion of the onboard fuel is directed to product tank for storage as the other of the cetane-rich fuel component and the octane-rich fuel component;
• and
• when using the controller to direct the flow of a portion of the onboard fuel to the separation unit:
• conveying a vaporized form of the adsorbate from the separation unit to a second compartment that is disposed within the first compartment of the fuel supply tank;
• condensing at least a portion of the vaporized by an exchange of heat with the onboard fuel that is present in the first compartment;
• conveying at least a portion of any remaining vaporized adsorbate from the second compartment to a third compartment that is disposed within the second compartment such that at least one of storage and additional condensing takes place in the third compartment;
• and
• conveying at least one of the cetane-rich fuel component and the octane-rich fuel component to the combustion chamber.