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EVALUATION OF EQUILIBRIUM OF VAPOR (EOEV) FOR FUEL STORAGE LEAK DETECTION

IP.com Disclosure Number: IPCOM000236096D
Publication Date: 2014-Apr-04
Document File: 1 page(s) / 328K

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The IP.com Prior Art Database

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EVALUATION OF EQUILIBRIUM OF VAPOR (EOEV) FOR FUEL STORAGE LEAK DETECTION

Vehicles sold in NA are required to perform Evap Leak Diagnostics. For federal states, a leak size of 0.04" needs to be detected. For green states, a leak size of 0.02" needs to be detected. Current EONV (Engine Off Natural Vacuum) uses pressure changes in a sealed system to validate no leak exists. This is a common practice within OEM's and uses a set of entry conditions to ensure its successful execution and obtain credible results. The authors proposed using Antoine's equation describing equilibrium vapor pressure as a mean to predict the vapor temperature or pressure, depending on the credibility of information. Antoine's equation approximates the relationship between vapor temperature (1/T) and vapor pressure (Log P) with a linear equation with two vapor property constants, A and B.

(1, Antoine's Equation)

Since gasoline mixture's vapor property constants can be interpolated with known mixture types such as E0 and E100, equilibrium vapor pressure / temperature can be estimated when some information about the mixture is known / approximated. This means constant A and B in equation in formula 1 can be obtained as weighted averages if mixture content and their ratios are known.

Method

In one application, if the vehicle has been parked for some period of time such that fuel sloshing effect has subdued and system temperature is close to ambient temperature. Plug in ambien temperature into...