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OAR Box 1818 

Prepped by Ollie Stewart 

Document Number: 

52) ll-D-24 

Docket Number: 

A-87-11 

Printed 11/6/2008 3:12:45 PM Sheet 52 of 79 
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dUtyjiU 

//-eO-Jflt 

NISSAN RESEARCH & DEVELOPMENT, INC. 

1919 Pennsylvania Avenue, N.W. 

Suite 707 

P. 0. Box 57105 

Washington, DC 20037 

Telephone 

(202) 466-5284 

April 14, 1987 

Ref: W-144-S 

Mr. Charles Gray 

Director, Emission Control Technology 

Division 

Environmental Protecxtion Agency 

2565 Plymouth Road 

Ann Arbor, MI 48105 

Dear Mr. Gray: 

Nissan appreciated the opportunity to meet with you on April 

1 for discussion of our feasibility study on onboard controls. 

Although you were busy with other pressing assignments, thank 

you for arranging to meet with us. 

Enclosed herein are responses to the questions that you and 

your staff asked at the April 1 meeting. I hope the enclosure 

fully answers your questions. However, if there are other 

items you wish to discuss about Nissan's analysis, please 

call me at any time. 

In reference to our discussion concerning confidential treatment 

of the materials submitted by Nissan during our meeting, we 

request that such materials be available for EPA's use and 

not distributed outside of EPA. According to our discussion, 

you indicated that it may be more convenient for EPA to use 

the materials under a request for restricted use, rather than 

for business confidential treatment. We request the same 

restricted use for the enclosed information, which is labeled 

"confidential." 

Thank you for your consideration. 

Sincerely, 

Li Shinbara 

Engineering Staff 

Engine & Emission Control 

end / 
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NISSAN MOTOR CO., LTD. 

SUPPLEMENTAL INFORMATION REQUESTED BY EPA ON ONBOARD CONTROLS 

1. Activated Performance and Temperature of Canister 

Figure 2-2(b) 

(1) Effect of rapid temperature increase on canister 

durability 

Durability testing is now being conducted. We expect 

to finish in June, 1987. 

(2) Reason that the activated carbon temperatures are 

higher in the 3.4 liter canister than in the 1.3 

liter canister 

The temperature of the activated carbon is determined 

by both the HC adsorption capacity where the 

temperature was measured, and heat transfer in the 

canister. Table 1 shows that the heat transfer of the 

canister casing (steel) in the 3.4 liter canister is 

larger than that in the 1.3 liter canister (plastic). 

However, Table 1 also shows that activated 

performance (absorbed HC amount per liter of carbon 

at a certain charging rate) of the 3.4 liter canister 

is larger than that of the 1.3 liter canister, and 

thus, that the heat generation caused by HC 

adsorption is higher in the 3.4 liter canister than 

in the 1.3 liter canister. 

From Table 1, we predicted that the temperature 

increased not because of a large heat transfer 

through the canister casing material, but because the 

activated performance is higher in the 3.4 liter 

canister, which results in greater heat generation. 

Since this data was measured up to canister 

breakthrough, we deem it necessary to study 

temperature differences due to both location of the 

temperature measuring device and adsorption 

distribution. 

The horizontal axis of Fig. 2-2(b) indicates the time 

after the temperature at the center of the carbon 

canister starts to rise. Actually, this time does 

not reflect the adsorption time. The commencement of 

adsorption in the canister was approximately one 

minute before the temperature began to rise for the 

1.3 liter canister, and was approximately twelve 

minutes before the temperature began to rise in the 

3.4 liter canister. The charging rates for both 

canisters was 5 g/minute. 
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The charging air temperature rises due to its passage 

through the high temperature areas. Those areas are 

caused by already adsorbed HC. Therefore, the 

commencement of the temperature rise does not 

correspond to the start of HC adsorption at the 

center of the carbon canister. 

If, however, the increasing temperature of the 

charging air is neglected, and we assume that the 

charging air spreads uniformly throughout the 

canister, the rate of temperature increase for the 

larger canister may be lower than that for the 

smaller canister (when the charging rates and HC 

charging amounts are equal). 

2. Test Condition of Figure 2-2(c) 

The charging rate is not 80 g/min, but 5 g/min as 

listed. 

3. Cross Section of Canister of in Figure 2-2(e) 

Each of the canisters are rectangular, but the sizes 

are different: 

Type A; 298 mm x 112 mm 

Type B; 210 mm x 108 mm 

Type C; 263 mm x 78 mm 

4. Influence of RVP on Emission - Figures 2-3(a)-(c), 

Table 2-3 

Figure 1 shows the relationship between RVP and 

emissions. As RVP increases, the canister capacity 

must increase because more gasoline vapor is 

produced. Also, the HC purge must increase to 

maintain adsorption performance. Therefore, the HC 

purge increase would cause emissions to worsen. 
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5. Canister Installation 

(1) Why the canister cannot be installed in a crush zone 

It is necessary to reinforce the body structure when 

placing the canister in crush zones. In FF vehicles, 

if the canister is installed in the rear crush zone, 

fueling parts such as the fuel tank and filler tube 

would be located in front of the canister. In order 

to prevent the canister from damaging the fueling 

system in case of impact, body reinforcement is 

necessary. 

(2) Why the canister cannot be installed in the bumper 

Installation of a canister in the bumper would be 

difficult because of space constraints. There is no 

available space for the canister in the bumpers of 

Nissan's current LDVs (Fig. 2). 

The current bumpers used in Nissan vehicles consist 

of a plastic cover filled with a foam material, a 

thin steel sheet, and a space for absorbing impact 

energy. Upon impact the bumper deforms to prevent 

vehicle body deformation. The space inside the 

bumper is needed for bumper deformation. If there is 

less space inside the bumper, or if the space is 

filled by a stiff object such as a canister, the 

requirements in 49 CFR Part 581 (bumper standards) 

would be violated. 

Current Nissan bumpers recover after small impacts, 

thus saving the consumer the inconvenience of bumper 

replacement after minor accidents. Since the bumper 

deforms easily, the canister in the bumper could be 

damaged by even very small impacts. The back 

pressure due to broken casing, bent tubing, or broken 

carbon can render refueling difficult or even 

impossible, necessitating canister replacement. 

Even if refueling were not hampered by the damaged 

canister, a cracked casing will leak vapors without 

the consumer's knowledge. 

In the case of LDTs, rear bumpers are not installed 

as standard equipment. If the canister were 

installed in the front bumper, the system would be 

susceptible to vapor line blockage by condensed 

vapors. 

(3) Why the canister must not be damaged 

There is no safety problem unless canister damage 

results in fuel leakage. 
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(4) Can the roll-over valve prevent fuel leakage even 

with canister damage? 

Nissan's vent cut valve can prevent fuel leakage, 

even with canister damage. 

6. Back Pressure Increase Caused by Liquid Gasoline 

Figure 2-5 

(1) Conditions for gasoline accumulation in the vapor 

line. How much gasoline vapor condensate can 

accumulate in the vapor line ? 

Warm gasoline vapor condenses in the vapor line when 

it contacts cold piping surfaces in the vapor line. 

For example, condensation occurs after high load or 

rush-hour driving in the winter. Our experiments 

indicated that 5-6 cc of gasoline could condense in 

the vapor line with an ambient temperature of 5 

degrees C and a fuel temperature of 26 degrees C. 

Although the worst conditions of condensed gasoline 

accumulation have so far not been identified, more 

gasoline may condense in the vapor line with 

conditions other than noted above. 

(2) Can a vapor liquid separator in the vapor line 

prevent condensation? 

We predict that gasoline condensed in the vapor 

liquid separator will not evaporate when the 

temperature is low, and may spill into the vapor 

line. 

(3) Is there gasoline condensation in the existing 

evaporative system ? 

There may be, as noted above. However,since there are 

no seals in the existing evaporative system when 

refueling, gasoline condensation does not affect 

refueling performance. 

(4) Won't higher RVP fuel cause less gasoline 

condensation? 

We have experimented only with 11.5 RVP gasoline and 

do not yet have condensation data with different RVP 

levels. 
P.7 

7. Effectiveness of the submerged liquid seal for the 

gasoline tank of the 300ZX — Figure 2-15 

The filler tube of the 300ZX is attached to the lower 

portion of the gas tank. It will not function as a 

liquid seal after the fuel inside the tank decreases to 

the half-way point. We have not confirmed its 

effectiveness as a seal, but we have not found any 

problem in the existing design. A J-tube filler pipe 

will probably be used in Nissan's onboard system. 

8. Refueling Performance — Figure 2-16 

(1) What is the maximum possible refueling rate in 

existing vehicles? 

It is possible to have refueling rates of up to 12 

gallons/minute for some existing vehicles. However, 

we have never attempted refueling at rates greater 

than 10 gallons/minute for onboard systems. 

(2) Is it possible to refuel to 95% of tank capacity at 

10 gallons/minute before shutoff? 

In existing systems it is possible to exceed 95% of 

tank capacity before shutoff in some models while 

refueling, but most models fall between 90 - 95%. 

For the onboard liquid seal system, we have not yet 

been able to establish a method which allows even 90% 

refueling. 

(3) Would there be a cost increase for refueling rates 

greater than 10 gallons/minute? 

Nissan has not yet conducted research on this issue. 

However, the following changes may be necessary: 

a) In order to decrease the pressure loss of the 

ventilation system, the tube diameter, the vent 

cut valve size, and the over-fill valve size 

must be increased. 

b) In order to decrease filler tube resistance, 

the tube system has to be redesigned, and the 

diameter of the filler tube has to be 

increased. 
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(4) Will there be a cost increase for 90% refueling and 

95% refueling? 

This has not yet been calculated, but a cost increase 

is likely. 

(5) The SAE refueling procedure 

According to our experiments using a liquid seal, 

vapor generation decreased as the refueling rate 

decreased. However, emissions from the filler pipe 

increased because of the lower velocity of the air 

entering the filler pipe (see the results below). 

Therefore, the SAE refueling method is not a 

favorable procedure for satisfying the refueling 

emission regulation. 

Refueling Speed (gal/min): 5.3 10.0 

HC Vapor Emission (g/gal): 0.15 0.075 

9. Lambda Control Under High Temperature Conditions 

(Figure 2-18(b)) 

The data shown in Figures 2-18 in the technical 

document is derived from testing a saturated canister 

in an integrated system. The change in the air/fuel 

ratio in the purge line just past the saturated 

canister with a two mm purge orifice is shown in Figure 

3 attached. 

These figures in 2-18 show that the total air/fuel 

ratio introduced into the combustion chamber exceeds 

the boundary controlled by lambda. 

10. Cost Estimation — Table 3-1 

a. Hose and Tube (see table 2) 

We estimated the cost for the hose and tube with 

the following specifications. 

•Diameter 

Charge Side: 

Fuel tank to canister 

Canister to ambient air 

The external tube diameter is 15 mm (internal 

diameter: 13.6 mm) so as to minimize the back 

pressure during refueling and to ensure refueling 

performance. 
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Purge side: 

Canister to engine 

The external tube diameter is 10 mm (internal diameter: 

8.6 mm), in order to handle the different flow volumes 

that a variable orifice control valve can supply. This 

is necessary because the vapor flow volume can rise to 

more than three times the volume of the current 

evaporative system. 

*Tube Material 

We used single-wound steel tubing, which is copperplated on the inside, and plated on the outside with 

copper and zinc, and coated with resin. 

*Hose Material 

We used non-reinforced NBR hose for the inside and CR 

for the outside. 

A detailed piping cost estimate for a Nissan 300ZX is 

shown in Table 2. 

b. Variable Orifice Control Valve 

Figure 4 shows the variable orifice control valve 

structure and the cost for the unit with a duty control 

valve. 

c. Canister 

The cost estimate for the canister is shown in Table 3. 

11. Time Schedule for the Introduction of the Onboard 

Control Test Facility — Figures 3-3, 3-6 

The standard time required for onboard control test 

facilities is ten months. This time interval covers the 

facility design (including the fuel supply system), 

necessary budget procedures, construction, and 

compliance with municipal building regulations. At 

least eight months are required even if this schedule is 

shortened to the greatest degree possible. 
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12. Cost Increase in the Case of Two Years Lead Time and 

Phase-In Adoption — Appendix III 

The calculation results are shown in Table 4. The 

calculation method is the same as described in Appendix 

III. 

13. Sales Volume Percentage of New Models Equipped with the 

Onboard Control System for Each Model Year — Appendix 

III 

Table 5 shows the sales volume percentages of new models 

for each model year when onboard controls are adopted by 

a phase-in plan starting with the 1993 model year (four 

years lead time). 
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TaibAes / — S 

* /* / - y 

CONTIDCNTUL