De-icing operations at Minnesota Saint Paul

Executive Summary

This study explains the consequences of research into how de-icing operations at Minnesota Saint Paul could be improved. The findings were that this airdrome should utilize a combination of infrared warming and antifreeze crop-dusting in order to defrost aircraft in a fast, safe, cost effectual and environmentally friendly manner. The de-icing procedure is called the `` thrust through method '' and this study has backed up its probe through elaborate computations and the usage of a determination matrix to compare the benefits of the thrust through method against utilizing others. Although there are some jobs such as its comparatively long payback clip of 2.5 old ages, plus risk the airdrome may hold to pay license fees due to patents on the engineering, the benefits of the thrust through method outweigh these drawbacks. One ground for this is that after the payback period the airdrome will do an one-year economy of about $ 7,080,000

Introduction

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The procedure of taking ice, hoar or snow from the surface of an aircraft is known as aircraft de-icing. This is an indispensable process because if these substances accumulate on an aeroplane they will magnify the retarding force force that the plane experiences. This will cut down the ability of its wings to bring forth adequate lift force to let it to take-off or tactic whilst in flight. Besides, harm could be caused if a big piece of ice dislodges from the plane and hits sensitive constituents like its engine. This could take to riders losing their lives in a clang and others losing their belongingss. The Federal Aviation Administration, FAA, modulate all major civil air power operations in America. One of their regulations is that aircraft must be free of ice before takeoff and during flight.

This study uses Minneapolis Saint Paul ( MSP ) airdrome, Minnesota, as its primary instance survey. This is because aircraft at this airdrome often needs to undergo make up one's minding as a consequence of the cold clime before, during and after winter in that part. MSP airdrome ps 3,400 estates, has five tracks, five de-icing tablets and `` served more than 32 million travelers in 2009 doing it 15th in the United States andA 30th in the universe in footings of figure of riders served yearly. '' ( MSP Airport, 2010 )

De-icing is presently carried out at MSP airdrome by operators who spray an ethylene-glycol based aircraft de-icing fluid onto planes. Storm H2O drains to roll up the waste fluid, before it is transported by a truck to a recycling installation to be treated. It needs intervention because its high Biochemical Oxygen Demand ( BOD ) makes it harmful to the environment.

This probe aims to happen a method and chemical to utilize for de-icing planes which is more environmentally friendly, cheaper and faster than that which is presently used in MSP airdrome.

It should be a `` entire solution engineering '' which eliminates/reduces all the jobs that the current de-icing method causes without bring forthing damaging side effects.

These purposes will be achieved by finishing the undermentioned aims:

Identify a replacement de-icing fluid which has the same/better de-icing functionality but costs less and is safer than the one presently used in MSP airdrome.

Find a better manner to recycle the waste de-icing fluid

Ensure that the new utility chemical allow de-icing fluid to be recycled

Find another manner to take snow from aircraft

Generic Design Process

Administrations frequently use a generic design procedure as they turn a merchandise thought into a manufactured point. Using a systematic, good organised designed procedure helps to cut down the research and development clip that a fresh merchandise experiences. The design squad for this undertaking used a generic design procedure and the actions that they took at each phase are detailed below:

Merchandise Planning - First the squad used merchandise planning to assist do that dependable and valid research was carried out directly off. This started this by keep backing a treatment in which they clarified the purpose and aims of the undertaking. Then they identified their strengths and failings in relation to these aims to assist them take which responsibilities they were responsible for. Finally they agreed upon timescales in which to accomplish each aim.

Designation of Customer Needs - Customers demands guided the squad 's merchandise inventions that were found. The squad held interviews with a representative from each major stakeholder group in the air hose industry, such as the air hose director and spray operator, to let them to voice their demands. This made it easier for the squad to put merchandise specifications and design a merchandise that they would O.K.

Constitution of Product Specifications - The client demands were ranked in order of their importance. The rank of each demand was relative to a weighting, tungsten, which was later used in a determination matrix. This information was used to bring forth merchandise specifications which were further defined utilizing prosodies.

Coevals of merchandise thoughts - A insight was held to bring forth merchandise thoughts. This was utile because it encouraged the squad to construct thoughts on top of one another. From this they saw similarities between thoughts and linked some of them to specify a entire solution engineering.

Choice of merchandise thoughts - A determination matrix was used to quantitatively compare the importance of each client demand in relation to the merchandise thoughts. The merchandise with the highest mark was selected for proving.

Testing - The entire solution engineering was further evaluated in footings of its public presentation and economic viability. Because it was really good its specifications were was sent to industries so that they could construct a paradigm.

An illustration of the generic design procedure

Figure 1 illustrates the merchandise design methodological analysis which begins with merchandise planning and ends with proving and industry. The flecked lines show that if one phase of the design procedure did non give advantageous consequences the squad would travel one or multiple phases back in order to polish their old purposes. Then they would progress through each phase of the procedure once more until they reached the concluding testing and fabrication phase. This process of measuring and re-assessing merchandise developments ensured that hapless designs were eliminated or improved before they reached the testing and industries phase.

Assorted clients have an involvement in aircraft de-icing operations ; these persons are referred to as stakeholders. The success of this venture will depend on how good it meets the demands of these persons. Hence, the squad evaluated each stakeholder 's demand utilizing an interview and ranked it harmonizing to its importance.

The stakeholders were identified on the footing on who will pay for, sell, usage and run the de-icing engineering, these included air hose pilots and riders etc. They were interviewed and their responses are summarised below.

Q1: How do you defrost a plane?

`` A container on a truck is filled with de-icing fluid which is assorted with H2O to a 50 % concentration by volume. I sit in an enclosed cabin and heat the fluid onboard the truck to 70oC before I spray it onto the plane until all the ice thaws. ''

Q2: How of import is the BOD of a de-icing fluid?

`` Very of import, we pay the intervention works about $ 0.35 per US gallon and the monetary value goes up if the BOD additions. Our airdrome is fined if the BOD5 discharged to the environment exceeds 900 metric tons per twelvemonth.

Q3: How long would you anticipate to wait for a return on your investing?

`` 1.5-2 old ages ''

Q4: How much does ethylene glycol cost?

`` The norm is $ 5-7 per gallon. ''

Q5: What safeguards were taken since your last incident?

`` We thought of retraining staff, but now operations are run by an outsourced concern.

De-icing tablets and a drainage system were installed. ''

Q6: What do you believe of incorporating a warming system onto aircraft?

`` Not ideal for commercial planes because it 's expensive ''

Q7: How severe is the break caused by aircraft de-icing?

`` During the extremum of the winter season there are regular holds. Aircraft must be de-iced once more if they exceed a holdover clip of 5 proceedingss. ''

Ranking of demands and 'sanity check '

The squad identified the most of import stakeholder demands and ranked them as listed below.

Each demand was given a weighting, tungsten, harmonizing to its rank as portion of a 'sanity cheque ' .

Table 1 - The rank of each stakeholder demand and its weighting

Weight-ing, tungsten

Safety was the top concern of every stakeholder.

Aircraft at MSP airdrome can merely transport riders if they obey safety ordinances set by the FAA.

Some stakeholders disagreed on fiscal issues sing how much hard currency should be spent on certain points. e.g most spray operators would wish luxury de-icing cabins whereas airdrome directors would instead put the money. However, all stakeholders agreed that no de-icer with a high life-time cost would be acceptable.

Slow de-icing can do net income losingss due to detain flights.

Although the airdrome will be fined for doing inordinate pollution these costs are usually absorbed by clients.

Constitution Of Product Specifications

Most of the demands highlighted by stakeholders were expressed in a qualitative mode. They needed to be converted into specifications in order to avoid fiddling yet expensive betterments being made to MSP airdrome. To make this the worst instance de-icing conditions that could potentially take topographic point at MSP airdrome were defined and as portion of saneness cheque. Following prosodies were used set up specifications for merchandise and procedure design methods that could get by with the worst instance de-icing scenarios at the airdrome.

Specification 1 - Annual length of operation

The day of the months in which the planes will necessitate to be de-iced scopes from November to early April because on these day of the months the temperature in Minneapolis Saint Paul is below stop deading.

Therefore, any new de-icing method must be able to run through this period of 5 months and 1 hebdomad ( 157 years ) every twelvemonth. ( Figure 2 )

Figure 2- The mean last temperature in MSP every twelvemonth from 1971-2000

Specifications 2 - The instance survey aircraft and its ice coverage

The mass of ice on a plane was calculated utilizing a worst instance scenario, which was that one of the biggest commercial rider planes ; the Boeing-747 ( BBC, 2007 ) needed to be de-iced.

It was assumed that the top country of both its wings was covered by a 1cm thick bed of ice.

Flying country ( Boeing-747 ) = 541.2 M2 ( Airliners, 2010 )

Ice Thickness = 0.01m

Ice Coverage 100 %

Volume of ice on wings, Volice = 5.412 M3 ( App. 1, Eqn 1 )

Density of ice, I?ice = 917kg/m3 ( Kotz, 2009 )

Mass of ice, = 4962.8 kilogram ( App. 1, Eqn 2 )

Specifications 3- Heating Duty

Latent heat of merger of ice= 333 kJ/Kg ( Bird, 2003 )

Minimum warming responsibility = 1652.6 MJ ( App 1, Eqn 3 )

Specifications 4 - The utility de-icing fluid

The atmospheric temperature in MSP airdrome during the de-icing season is 20oF ( -29oC ) therefore the replacement ADF stop deading point must be less than 20oC in order to keep its functionality. Additionally it must supply a freezing point depression of more than 20oC as a consequence of this ambient temperature. All the stakeholders agreed that merchandise safety is of topmost importance, so the replacement ADF should be less toxic than ethylene-glycol. Additionally they agree that the one-year natural stuff costs of the new cubing method should be less than that of the current method. Two ways to make this are to utilize less cubing fluid per plane in the first case ; this should be less than the 408 gallons per aircraft required by the current de-icing method ( App. 1, Eqn. 9 ) , or to recycle the de-icing fluid.

Generation and Screening Of Ideas

The squad worked separately and brainstormed together to assist maximize the figure of good thoughts that were generated. Whilst making so they reflected upon the merchandise specifications to and stakeholder demands to assist test thoughts.

De-icing boots - Rubber boots are attached to the front borders of wings on the plane. The aircraft inflates these boots with air to do ice that take ice that has accumulated on them. An unacceptable hazard of utilizing this method in MSP is that the system must be activated every bit shortly as a before an big ice bed can organize and hit other parts of the plane when it dislodges.

Bleed air- In this method hot air from the aircraft engines is blasted on to the ice to run it. Although this could run ice really rapidly the airdrome director at MSP airdromes commented that incorporating heating systems on to aircraft is `` non ideal for commercial planes because it 's expensive '' .

Mechanical Scraping/Blowing

Employees use coppices, or fabrics to physically force ice off the aircraft. This method would be really easy to set into pattern at MSP because the equipment the required is really inexpensive. But it is more likely that harm will be done to aeroplanes as the employees scrape ice so the resulting aircraft care cost is could be really high.

A propene ethanediol based de-icing fluid - Propylene ethanediol is a popular de-icing fluid and is regarded as non-toxic, hence it was chosen for farther probe.

Decision Matrix

The interviews that were conducted with the stakeholders highlighted that some client demands are more of import than others. Although the importance of some specific demands differed in each stakeholder group four demands were systematically rated as indispensable.

These standards were analysed in a determination matrix with weighing Marks taken from Table 1.

Selection of Ideas

The most freezing point sedatives in aircraft de-icing fluids in the US are ethylene ethanediol ( EG ) and propylene ethanediol ( PG ) . Because PG and EG have a similar life-time cost, in this chapter the chemicals will be compared at a 50 % concentration by volume in footings of their safety, de-icing velocity and environmental impact because these are three of the most of import needs the stakeholders.

Ethylene ethanediol has a comparatively high toxicity when compared to Propylene-Glycol. It has been classed by the US Congress as a risky air pollutant ( HAP ) , if 2268 kilogram or more flights into the environment within 24 hours users are obligated to describe the event under the Comprehensive Environmental Response Compensation and Liability Act ( CERCL ) . However propylene ethanediol is non classified as a HAP, and users are non required to inform CERCL if it is released.

Both chemicals are said to be non-lethal if worlds if they are breathed in with air or adsorbed through tegument. However, unlike PG, EG is toxic to worlds and mammals if it is ingested straight. Even though PG it is regarded as non-toxic it is still a wellness jeopardy because it uses O as it biodegrades which could do some beings to smother.

The freezing point of Propylene-glycol is -34oC which is somewhat higher than ethylene-glycol which freezes at -37oC. This is one of the grounds why MSP airdrome still uses EG. Another is that a lower volume of antifreeze is required for EG to accomplish the same freeze point depression as PG.

MSP airdrome suffers severe conditions extremes so it needs to utilize an ADF which is dependable, particularly in highly cold conditions as this is by and large when it takes longer to defrost aircraft

Propylene-glycol 's boiling point is 106oC whereas ethene ethanediol has a boiling point of 102.2oC for ethene ethanediol. In this instance Propylene-glycol is the better pick because it can reassign heat to frost at a higher temperature than ethylene ethanediol.

There are some drawbacks with respect to utilizing ethylene ethanediol as a de-icing fluid, particularly refering its environmental impact. But, overall EG and PG have a similar de-icing public presentation degree.

The Rate of Melting due to Heat Conduction Entirely

The ADF is heated to 70oC before it is sprayed onto the plane, this heat entirely will do the ice to run through heat conductivity.

The rate of this warming was calculated utilizing equation 1a,

Where Q= is the heat flow rate in the X-direction in kJ/s, A is the country normal to the way of heat flow in M2, dT/dx is the temperature gradient and K is the thermic conduction of ice

The thermic conduction of ice at -20oC is 2.39 W/mK, the country normal to the way of heat flow is equal to the flying country of the Boeing 747 =541.2m2, the temperature alteration that occurs is ( 70oC- -20oc ) =90oC and the thickness of the ice x is 0.01m.

Therefore the rate of heat transportation by the temperature of the de-icing fluid alone is

The reasonable heat is kJ ( App. 1, Eqn 12 )

The latent heat of merger is 1652612.4 kJ, ( App.1, Eqn 3 )

Summarizing the above gives the sum of het required to run the ice on a Boeing 747 from a starting temperature of -20oC which is

Hence minimal clip that it would take to run the ice on the plane by heat conductivity entirely is

This is a really fast clip, particularly as harmonizing to the undertaking brief, de-icing at MSP airdrome usually takes 10 proceedingss per plane. One ground ground for this difference is due to the fact that the ADF fluid is non ever in full contact with ice, merely its bottom surface is. Additionally these computations assume that heat transportation occurs over the whole of each flying equally, which is non the instance in existent life because de-icing fluid is sprayed onto the wing in different locations consistently. A concluding cause of this difference could be due to the fact that snow has a lower heat conduction, K, than ice and so any snow on a plane would take down the rate of heat transportation from the ADF.

Entire Solution Technology

The concluding design construct was to carry on de-icing operations as a thrust through system.

First the aircraft enters the Infrared air dock where and warm air blows snow of its wings whilst they are heated by infrared radiation for a typical continuance of 5-10 proceedings. Ice on the plane thaws onto an inclined incline and the effluent is channelled into the waste aggregation zone.

Water is channelled through bing storm H2O pipes into substructure to the located under the floor of the crop-dusting and waste aggregation country. The effluent is pumped out and transferred by a truck into the airdrome 's detainment pools.

When the effluent has been removed compaction stoppers are removed and the plane moves into the spraying country. Here it is sprayed with propene ethanediol for up to 5 proceedingss to assist forestall any ice forming on it before takeoff.

The propene ethanediol drains into a separate country of the aggregation chamber and is pumped to a detainment pool until it is due to be recycled. Finally the compaction plus are reinstalled so the system is ready to defrost another plane.

Minneapolis presently uses three Glycol Recovery Vehicles to roll up effluent. Using the IR installation eliminates the demand to defrost aircraft utilizing ethanediol by around 90 % , so no more of these vehicles will necessitate to be bought if the new engineering is adopted. Besides the airdrome has saved capital costs by utilizing their bing storm H2O drains to roll up both ethanediol and storm H2O. These storm drains can and should go on to be used if MSP airdrome adopts the Drive-Through De-icing system to salvage hard currency and clip during the installing of the new system. Harmonizing to ( Big book ) `` Careful direction of the keeping systems enables the airdrome to roll up adequate effluent with high ethanediol concentrations to do glycol recycling/recovery economically feasible. '' The bulk of ethanediol which is recycled is sold to makers who use it in other glycol-based merchandises.

Unfortunately the payback clip on the thrust through de-icing method is non fast plenty to fulfill the Airport Directors at MSP who expect a payback clip of `` 1.5-2 old ages '' . A higher rate of return on investing would cut down the payback clip so it would be wise to look into extra ways to cut down the cost of de-icing utilizing this engineering, and ways to better its efficiency.

Because this entire solution engineering uses de-icing methods which have been used in industry antecedently, but it combines them in a alone manner it is hard to measure whether or non it can be patented. Furthermore, it is expected that it would take a long clip to patent the merchandise even if it were possible because of its complexness and usage of old de-icing thoughts. The writer has recommended that MSP airdrome consults a attorney sing these affairs if they do non necessitate to utilize the de-icing solution instantly. If MSP airdrome do necessitate to utilize the engineering instantly they might hold to pay licence fees to one or more patent proprietors.

The findings from this probe have shown that the solution engineering that MSP airdrome should utilize to better its aircraft de-icing solution involves utilizing infrared warming and a propene ethanediol as a utility chemical for ethylene-glycol. The procedure is called the `` thrust through method '' and the major advantages of this intercrossed solution are that it meets the demands of its stakeholders by being safe, holding a low life-time cost, fast aircraft de-icing rate and low environmental impact. Evidence of this has been provided through a determination matrix and several mathematical ratings.

Unfortunately this solution has a payback clip of 2.5 old ages, so research should be carried out to uncover how to do the one-year rate of return on the investing higher. Finally, this intercrossed system uses patented engineering so MSP airdrome might hold to pay license fees for a figure of old ages if it used the thrust through method. However, after the payback period the one-year economy of $ 70,844,300 per twelvemonth outweighs any of these drawbacks.

Find ways to cut the operating cost of the Drive-Through De-icing system as this will raise the one-year rate of return that this engineering provides. If the rate of return is high plenty the payback clip will drop below 2 old ages and the airdrome directors in MSP will hold this demand fulfilled.

Use hot air to blow snow off the aircraft in the IR air dock. This will assist to run the snow and ice excessively, nevertheless the cost of warmin+

3.0g air may countervail the benefit of a faster de-icing clip. Nb, as shown by the weightings, tungsten, in Table 1, the life-time cost of the engineering is more of import that the de-icing velocity that it provides.

Mentions

1. Bird J.O. , 2003, Science for technology, pp. 205, Newnes, 2003, UK
2. Ketler P. , Mosher M. , Scott A. , 2008, Chemistry: The Practical Science, media enhanced edition, Cengage Learning, pp. 478, UK
3. Kotz J.C. , Paul T. , Townsend R.J. , 2009, Chemistry and Chemical Reactivity, Cengage Learning, pp. 15, USA
4. Tsokos K.A. , 2010, Cambridge Physics for the IB Diploma, pp. 172, Cambridge University Press, UK
5. Sinnot R.K. , 2005, Coulson and Richardson 's Chemical Engineering Series: Chemical Engineering Design, pp. 439, Butterworth-Heinmann, UK
6. MSP Airport, 2010, About Us, hypertext transfer protocol: //www.mspairport.com/about-msp.aspx, 24/10/2010
7. RSS Weather, 2003, Minneapolis-St. Paul, hypertext transfer protocol: //www.rssweather.com/climate/Minnesota/Minneapolis-St.Paul, 23/10/10
8. Airliners.Net, 2010, The Boeing 747-400, hypertext transfer protocol: //www.airliners.net/aircraft-data/stats.main? id=100, 20/10/2010
9. BBC, 25/10/2007, A380 superjumbo lands in Sydney, hypertext transfer protocol: //news.bbc.co.uk/1/hi/world/asia-pacific/7061164.stm, 19/10/2010
10. Energy Information Administration, October 2010, Electric Power Monthly, hypertext transfer protocol: //www.eia.doe.gov/cneaf/electricity/epm/epm.pdf, 15/10/2010
11. Wingss Magazine, 2007, Infrared De-icing: Giving glycol a tally for its money, hypertext transfer protocol: //www.wingsmagazine.com/content/view/1325/38/ , 23/10/10

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