Product RD Session 4 - Pushcart Case Study Part 2- Jan 2013

7/29/2019 Product RD Session 4 - Pushcart Case Study Part 2- Jan 2013

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Product Research & DevelopmentSession 4

Case Study of

Pushcart for Vending Ice-Cream

Part 2

Department of Chemical Engineering

2nd

Semester 2012-2013

V. M. Naik


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Objectives of the Case Study:

Illustrate the Steps, and Stages Involved in

Product R&D, and the Nonlinear Nature of the

Whole Process

Illustrate the Skills and Competencies Required

to MAKE AN INVENTION AND INNOVATIONHAPPEN


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The Background

An MNC Built an Ambitious Modern Plant for Ice-Cream, in

India, and Set up a Unique Supply Chain to Improve

Availability of Quality Ice-Cream to Consumers, in 1990s

CITY COLD

STORES

++ ++

REFRIGERATED

TRUCKS

REGIONAL

COLD

STORES

REFRIGERATED

TRUCKS

RETAIL CABINETS

VENDING PUSHCARTS

FACTORY

COLD STORE


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Background Continued.

Ice-Cream Is a Delicately Structured Multiphase CompositeSystem. It Should Be Stored and Served at ~ -18Deg C forConsumers Safety and Delight

Therefore Vending Push CartsWere an Important StrategicBusiness Imperative forIncreasing the Availability ofIce-Cream to Consumers

++


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Schematic Design of the Original Push CartDeveloped Jointly by the Indian Business and a Laboratory in The

Netherlands

35 Kg of 35%PG-Water Eutectic Frozen to -25 deg C

Employed as Nontoxic Coolant

Poly Urethane

(PU) Foam

Insulation

Eutectic

CoolantJacket

Freezeron

Wheel++


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Market Response

Vendors Complained That the Push Carts Were TooHeavy and Difficult to Push

Consumers Complained That the Ice-Cream Was

Soggy When Purchased in the Afternoon

Ice-cream Sales Were Far Below Break-even Level

An Unrelated Discussion with the Business Head of

CAME Region, Regarding the MAP-DAP Eutectics

Triggered the Subsequent Events

The Needs of Both, the Customers and Consumers

Were not Met


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CASE STUDY OF ICE-CREAM VENDING PUSH

CARTS Business Sent a Technical Brief to Research

Develop a Rigorous Theoretical Model of the

Pushcart and Improve the Performance of the

Non-Toxic 35%PG-Water Eutectic Coolant

System So That:

The Pushcarts Can Deliver Non-soggy Ice-

Cream for at Least 10 Hrs

AND, If Possible

The Coolant Quantity Can Be Reduced from

35 Kg to 20 Kg, to Achieve a Reduction in the

Weight of the Push Cart by 15 Kg


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CASE STUDY OF ICE-CREAM VENDING PUSH CARTS

The First Step Was to Perform Reality Checks on the

Technical Brief from Business


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One Must Learn to Make Quick Back of the Envelop

Estimatesfor Reality Checks

Next Reality Check:

Estimate the Expected Cooling

Capacity of the Eutectic

Reality Check1:

What Could Be the Maximum Extent of Heat Ingress (DH) through

PUF Insulation of the Walls of the Cabinet in 12 Hrs?

DH = A * k * DT * t / l

~ 3600kJoules

Please Note : For a liberal

estimate ofDH, one can neglect

the resistance by air films, and

use the (larger ) outer surfacearea

Tin=-200C

Tout=+300C

0.9 m

0.6m

Insulation:

k = 30 mW/m oC

l = 75 mm


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One Must Learn to Make Quick Back of the Envelop

Estimatesfor Reality Checks..

Reality Check 2:

What Is the Expected Latent Heat of Melting for the 35% PG-WaterEutectic System?

DH of Melting = ~ X water* l m Water

= ~ 200 k Joules/kg

Please Note : For a quick

conservative estimate ofDH for

melting, the heat ofmelting/dissolution of the solute

was neglected

Typical melting

curve of eutectics

Temperature

Enthalpy/Kg

MeltingofEuMix

TEu


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Findings from Back of the Envelop

Reality Checks 1&2

Latent Heat of Fusion of PG-Water Eutectic

Containing 65% Water~ 200 KJ/Kg

Likely Heat Ingress in to the Box, through

Insulation, over 12 Hrs ~ 3000 KJ

Therefore the Theoretically Estimated Quantity of

Eutectic Coolant Required to Counter the Heat

Ingress for 12 hrs : ~ 15 Kg Maximum (as against 35

Kg Actual)

What Was Likely to Be the Source of Discrepancies?

Next Steps : Verify Data and Assumptions


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Conclusions:

1. 35% PGWater Was Not an Eutectic System and Its

Cooling Capacity Was Far Short of Theoretical

Estimates/Requirements

2. There Was Definitely a Need for Improvement of the

Eutectic System.3. Was the Design of Pushcart Acceptable.? Not Sure

D H = < 30 KJ/Kg

Reality Check-3:Experimental Verification of Latent Heat of Melting of 35%PG-Water Eutectic

Using Differential Scanning Calorimetry (DSC)


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Case Study Continued.

Next Steps :

Additional Information Gathering, and FirstPerson Observations/Discussions on the

Field, to Better Understand the Issues, as Well

as for Deciding the Way Forward


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Visits to Cold Store, Vendors, and Development

Department

Discussions with Customers/Fabricators/Development Team Regarding

New Ideas and Their Feedback:

(i) Electric Supply Unreliable

(ii) Refrigerants in Use Not Suitable for Cooling the Eutectic below 30 Deg C

(iii)Detachable Freezer Couplings not Reliable

(iv) There Is No Better Coolant or Insulation Available in the World (!)

(v) Dry Ice Poses Supply Chain as well as Safety Issues

Field Observations:

(i) Quick Ingress of Hot/Humid Air, When Lid Is Opened(ii) Equilibration of Air Temperature with Surroundings,

in a Short Time

(iii) Steady Ingress of Heat through Insulation,

Heating/Melting of Coolant, and Slow Rise in Ice-Cream

Temperature


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New Important Learnings:

Performance of Pushcart Depends on Several Coupled

Factors and Processes. We Must Have a DependableTheoretical Modeling/Simulation Tool to Validate/Rank

Quality of New Candidate Ideas for Performance

Improvement

We Must Co-invent the New Pushcart Design, and

Eutectic System, if We Want to Succeed


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Next Step:Build Theoretical Model For Predicting Heat Ingress and Ice-

Cream Melting

How Do You Build a Model for Multiple Coupled Phenomena with Vastly

Different Time-scales within a Short Time and with Limited Resource?

The Physical Model

Enthalpy Temp Diagram

for Cornetto Ice-Cream


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17

Building Theoretical Model For Predicting Heat

Ingress and Ice-Cream Melting : The Way-forward

Simplify Model by Decoupling Modeling of the Three Processes Which

Operate at Three Distinct Time-scales, Viz. (i) Quick Ingress of Hot Air

When Lid Is Opened, (ii) Equilibration of Air Temperature with Surroundings,

(iii) Steady Ingress of Heat through Insulation, Heating/Melting of Coolant

and Slow Rise in Ice-Cream Temperature

The Physical Model

Enthalpy Temp Diagram

for Cornetto Ice-Cream


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Theoretical Model For Heat Ingress and Ice-Cream

MeltingResult 1..Quick Air Ingress and Its Rapid Equilibration


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Theoretical Model For Heat Ingress and Ice-Cream

MeltingResult 2 . Slow Heat Ingress through Walls of Container

Comparison of Result 1&2 with Field Data Confirmed That the

Modeling Methodology

The Model Was Ready for Evaluation of

Alternative Ideas


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Generation of New Ideas and Their Evaluation

Using the Theoretical ModelIdeas Generated in the Class Room

Provide Sealed Dispensing System Store Ice-cream in Different Compartments

Provide Cold Air Curtain/Internal Source of Cold Air

Increase Mass of PG-Water

Motorize the Pushcart

Change the Composition of PG-Water

Use a New Genuine Eutectic Coolant

Increase Cooling Surface Area by Putting Frozen

Eutectic in Small Ampoules

Make Cylindrical Pushcarts to Reduce Area/Volume

Ratio

Use Better Insulation


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Will Reducing Air-ingress Result in Substantial Performance

Improvement?

Answer : NO


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Will Increasing the Weight of PG-Water System

Solve the Problem?

Answer : NO


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Will Changing PG-Water Proportion Help?


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Will Changing PG-Water Proportion Help?

Answer : NO
http://3.bp.blogspot.com/_JLeMz4WY6MM/TFD9xEDgGhI/AAAAAAAABvg/1pGsHrfHET8/s1600/propyleneGlycolPhaseDiagram.jpg


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Will Use of a Genuine Eutectic with Teu= - 26 Deg Help?

No Success


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Will Use of Genuine Eutectics with Much Lower Teu Help?

Option Not Acceptable Due to Refrigeration Constraints


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Will Use of Additional Coolant Pads for Increasing Coolant

Surface Help?

No Success


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Evaluation of Ideas.

What Next?


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A Principle to Remember :

Problems Cannot Be Solved by Thinking Within the

Framework in Which the Problems Were Created

Albert Einstein

O


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Important Observations Which Prompted

Conception Of A New Breakthrough Idea

The Push Carts, and Therefore the Model Developed to

Simulate Their Operation, Involved a Competition Between

Two Heat Sinks viz. Ice-Cream and Coolant

In All Alternatives the Coolant Was Not Fully Molten and

Yet Ice-cream Temperatures Rose Above - 18 Deg C


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Genesis Of A Novel Breakthrough Idea

Why Not Put The Two Heat Sinks In Series With Each Other

Vs


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This Involved Modifying the Model to CheckPracticality of the Idea

Thi I l d Eff t t M dif th M d l


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This Involved Efforts to Modify the Model

But the Result Was Worth the Effort

A Novel Design for The Push Cart Was Born


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The Magical Result

HEAT SHIELDHEAT SINK

Time (hours)

0 2 4 6 8 10 12 14

Ice-CreamT

emperatu

re(degC)

-21

-20

-19

-18

-17

-16

Heat Sink

Heat Shield


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The New Idea Was So Powerful That It Worked with

Even Higher Temperature Eutectics !


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What Next ?

File a Patent:

The Idea Is So Simple That It Can Be

Copied Very Easily. But It Is So Useful

That It Has to Be Protected as an

Intellectual Property


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What Next ?

File a Patent:

The Idea Is So Simple That It Can Be Copied

Very Easily. But It Is So Useful That It Has to Be

Protected as an Intellectual Property

Search for a Non Toxic, Non Corrosive Pure

Chemical, or Develop a Genuine Eutectic

System with High l, Which Melts between ~ 20

and - 26 Deg C

S h f N T i N C i P Ch i l


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Search of a Non Toxic, Non Corrosive Pure Chemical,

or Development of a Genuine Eutectic System with

High l, Which Melts between ~ 20 and - 26 Deg C

Likelihood of Finding an Eutectic Was Higherthan Finding a Pure Chemical

Ice-Cream and Cryogenic Industries All Over theWorld, Had Worked on This Problem WithoutMuch Success.

All Commercially Available Eutectic Coolants

Were Both Corrosive and Not Safe Enough.



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Likelihood of Finding an Eutectic Was Higher thanFinding a Pure Chemical

Ice-Cream and Cryogenic Industries All Over the World,Had Worked on This Problem Without Much Success

All Commercially Available Eutectic Coolants Were BothCorrosive and Not Safe Enough

________________________

How Do We Search for the Right Eutectic System?



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Search of a Non Toxic, Non Corrosive Pure Chemical, or

Development of a Genuine Eutectic System with High l,

Which Melts between ~ 20 and - 26 Deg C

A So Called Rigorous Rational Approach:

C1 C2 .

.

Cm

L1

L2

..

Ln

56 Million Components in

CAS Registry Would Lead to

!256!2

!56

M

M

Binary Combinations



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Likelihood of Finding an Eutectic Was Higher than Finding a PureChemical

Ice-Cream and Cryogenic Industries All Over the World, HadWorked on This Problem Without Much Success. All Commercially

Available Eutectic Coolants Were Both Corrosive and Not SafeEnough. Use of Expensive Materials of Construction to Counter the

Issues Was Not a Prudent, and a Viable Option in India. This Was Not a Rational Optimization Problem,

but a Complex Multi-dimensional CreativeChallenge.

Use ofHeuristic Insights about Phenomenologyof Solid-Liquid Phase Equilibria, SimplifiedTheoretical Thumb Rules, and a Hypothetico-Deductive Approach Was the Best Way

Forward.

Some Qualitative Observations on a Simple Binary


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Eutectic System Formed by Two Immiscible Solids

Congruous Melting



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43


Eutectic System Formed by Two Immiscible Solids

Congruous Melting

Eutectic Temperature of a Binary Mixture Is

Always Lower Than the Melting Point of Either

Component


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44

Some Observations On Ternary Eutectic Systems

Three Binary Eutectics

Usually Result in a

Ternary Eutectic, with

Melting Point Lower Than

Those of All Three

Components, and the

Three Binary eutectics

Composition of SuchTernary Eutectic Lies

within the Triangle

Formed by Three Binary

Eutectic Points


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If A Is a Solvent, and B a

Solute, The Heat Absorbed

During Eutectic Melting ~

XAlA +

XB D

H

SB-A-----------------------------------

What Do You Do to

Obtain an Eutectic withHigh Heat Absorption

Capacity?

Search For Suitable Eutectic : Our Approach

Congruous Melting


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If A Is a Solvent, and B a Solute,

The Heat Absorbed During Eutectic

Melting ~ XAlA + XB DHSB-A---------------------------------------------

What Do You Do to Obtain an

Eutectic with High Heat AbsorptionCapacity?

__________________

Choose a Solvent with High

and a Combination ofComponents Which Forms an

Eutectic Which Is Rich In

Solvent A.


Congruous Melting


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If A Is a Solvent, and B a Solute, the HeatAbsorbed During Eutectic Melting ~ XAlA +XB DHSB-A

---------------------------------------------

Choose a Solvent with High and a

Combination of Components Which Formsan Eutectic Which Is Rich In Solvent.

_________________

Water Is One of the Most Obvious

Choices of Solvent A.

Now How Do We Choose Solute

B ?


Congruous Melting

H D W Ch S l t B S h Th t It D M lti P i t


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How Do We Choose Solute B Such That It Depresses Melting Point

of Ice at Minimal XB & Forms an Eutectic at < - 20 Deg C ?

B

A

A ixRT

AforTl

2

D

Congruous Melting

+

D

+

D

A

A

B

B

A

A

A

mB

B

AA

mB

B

A

A

B

B

B

B

B

mA

A

BB

mA

A

MX

MX

MX

iRT

xiRT

BforT

Similarly

MX

MX

MXi

RT

xiRT

AforT

l

l

l

l

2

2

2

2

ThinkingCreativeeQualitativfor

ThumbrulesveQuantitatiSome

H D W Ch S l t B S h Th t It D M lti


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How Do We Choose Solute B Such That It Depresses Melting

Point of Ice at Minimal XB & Forms an Eutectic at < - 20 Deg C ?

B

A

A ixRT

AforTl

2

D

Congruous Melting

BA

BA

mB

BB

B

B

AB

mA

AA

A

A

B

B

B

B

B

mA

A

BB

mA

A

X

M

Mi

RTTBforTLiquidus

Similarly

XM

Mi

RTTAforTLiquidus

MX

MX

MX

iRT

xiRT

AforT

+

D

1



2

2

2

2

l

l

l

l

H D W Ch S l t B S h Th t It D M lti


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50

How Do We Choose Solute B Such That It Depresses Melting

Point of Ice at Minimal XB , & Forms an Eutectic at < - 20 Deg C ?

B

A

A ixRT

AforTl

2

D

Congruous Melting

B

A

BA

mB

BB

B

B

AB

mA

AA

A

A

B

B

B

B

B

mA

A

BB

mA

A

XMMiRTTBforTLiquidus

Similarly

XM

Mi

RTTAforTLiquidus

MX

MX

MX

iRT

xiRT

AforT

+

D

1



2

2

2

2

l

l

l

l

Look for Small Molecular Weight Well Dissociating Electrolytes Which

Form Eutectics with Water at Temperatures near 20 Deg C

Avoid Halides Corrosive

Avoid Nitrites .Toxic


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Employ Water as Solvent for Its Large Latent Heat ofMelting and Low Cost

Look for Low Molecular Weight Electrolytes Which FormEutectics with Water at Temperatures Near 20 oC

Avoid halides..corrosive Avoid Nitrites/Nitratestoxic

This Leaves No Choice from the Inventory ofFreezing Mixtures Reported in Literature

What Next ? Look for Edible Salts of Organic Acids

They are likely to be less corrosive as well



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52


Employ Water as Solvent for Its Large Latent Heat of Melting and LowCost

Look for Low Molecular Weight Electrolytes Which Form Eutectics withWater at Temperatures Near 20 oC Avoid halides..corrosive

Avoid Nitrites/Nitratestoxic

This Leaves No Choice from the Inventory of Freezing MixturesReported in Literature. What Next ?

Look for Edible Salts of Organic Acids

They are likely to be less corrosive as well

An Encouraging Finding :Sodium AcetateTEu = - 18

oC

What Next ?


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53

An Encouraging Finding : Sodium Acetate TEu = - 18oC

What Next ?

Further Lower the Freezing Point Using Other

Non Corrosive Binary-Eutectic Forming Edible

Salts

Eg DiSodium Phosphate, Sodium Carbonate

Adjust Composition Employing Heuristic/

Phenomenological Insights about Multi

Component Eutectic Systems, and Hypothetic-

Deductive Approach, to Obtain Genuine Ternary

or Quaternary Eutectic Point

The Result


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The Result

DSC

Temperature

-35 -30 -25 -20 -15 -10

HeatFlow

in

DSC

New MarkI

Eutectic

PG35%

Only the ThirdTrial Produced

the Mark I

Eutectic

Composition!

Was It a Fortuitous Accident?


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He Who Catches Plenty of Fish

Knows Where to Throw the Line

..A Chinese Proverb


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Documents

Product RD Session 4 - Pushcart Case Study Part 2- Jan 2013