energetic optimization of an improved cooking stove … · alvarez p.h.j. estudio de cocinas...

ENERGETIC OPTIMIZATION OF AN IMPROVED

COOKING STOVE FOR RURAL AREAS IN PERU

Work performed under the supervision of Prof. George Tsatsaronis and M.Sc. Natalia Realpe

Iulia Dolganova | SEER4ALL lecture series | 07.02.2017

Agenda

1. Introduction

2. Research question and objectives of the work

3. Theory

4. State of art

5. Possible solutions

6. Summary

7. Recommendations

Iulia Dolganova| SEER4ALL lecture series | 07.02.2017

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1. Introduction: background

In Peru, 34 % of the rural population uses solid fuels for cooking deforestation, health problems, etc. (INEI, 2015)

Open fire vs. traditional stove vs. improved cooking stoves (ICS)

Globalgrade (2014) Globalgrade (2014)

MEI (2014)


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1. Introduction: background

The Improved Cooking Stoves (ICS) Project of MicroEnergy International was implemented in rural areas

Implementation through microfinance mechanisms

access to good quality products for reasonable prices

Execution of market studies and validation tests

Three available models of ICS were tested in the beginning, one selected


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1. Introduction: ICS

ICS are designed in such a way to assist better combustion and heat transfer, for diminishing firewood use (in 30-35%) and for reducing intradomiciliary emissions

ICS must be safe to the end users, easy to use and guarantee low costs

ICS should be manufactured locally

Efficiency of an ICS: ηthermal, ICS = ηcombustion * ηheat transfer

ηcombustion larger than 90% (Aprovecho, 2002)

Increase ηheat transfer

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1. Introduction: problematization

Water Boiling Test. MEI (2014)

Variables Results

Initial temperature water in pot 1 [oC] 27,6


Time until the boiling of the pot 1 [min] 17

Boiling temperature of water in pot 1[oC] 99,2

End temperature of water in pot 2 [oC] 51,7

Efficiency of the system [-] 25%

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1. Introduction: problematization

Water Boiling Test. MEI (2014)

Variables Results



Time until the boiling of the pot 1 [min] 17

Boiling temperature of water in pot 1[oC] 99,2

End temperature of water in pot 2 [oC] 51,7

Efficiency of the system [-] 25%

Problem: The second pot

gets much less heat input

compared to the first one.

1. Pot: 0,91 kW

2. Pot: 0,52 kW


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2. Research question and objectives of the work

Is there an approach to improve the performance of the second pot without interfering majorly in the stove’s design and in such a way that it remains user friendly?

Main objectives:

1. Investigate the convective heat transfer in a prototype of

a Peruvian portable ICS with the help of experimentally

obtained data

2. Propose improvements to the stove’s performance by

enhancing the heat flow to the second pot


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3. Theory: heat transfer in a nutshell

Convection: matter dependent transport of mass, impulse or energy in flowing gas or liquids

Losses in the convective heat transfer: 22-39% of the total input to the woodstove (Zube, 2010)

Increasing convective heat transfer to the pot is the single most important way to increase thermal efficiency of a stove (Baldwin, 1985)

Increase

surface area Modify flow parameters

(mass flow rate,

temperature)


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4. State of art

Baldwin (1987) Heeden et al. (1986)

Kumar (1990) Bernilla (2005)


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5. Possible solutions

Social aspects

40% of families are not sure about the procedures to use an ICS (Peru, 2010). Risk of inacceptance

Improvement should be independent of extra user intervention/major change of habits

Economic aspects

80% earn less than 53 EUR/week (MEI, 2014)

Low payment willingness: 102 EUR

Production costs: 267 EUR

Respect local traditions, keep production costs low


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5. Possible solutions (1) – Elevation of the first pot

Idea: Elevation of the first pot, in order to diminsh the pressure losses of the system. Second remains submerged

Justification: A submerged first pot may block the flow to the second pot. Model „planchas“ delivered good results

Results:

Worse performance of the first pot (slower)

Lower losses in the system

Higher temperature of second pot (66 °C)


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5. Possible solutions (2) – Larger second pot

Idea: Increase the surface area of the second pot from 26 cm to 28 cm

Justification: Requests of the local population in the focus groups (MEI, 2014)

Results:

9% increase of the convective heat transfer to the second pot.

Pot hole larger as 28 cm is of no use for most households


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5. Possible solutions: (3) introduction of a baffle

Idea: Diminishment of the clearance height between both pots

Justification: Baffles reduce pressure losses to sudden expansion

Results:

Tpot2 7% higher than in the original prototype

Increase of 10% in the efficiency

Baffle size must be carefully planned and tested

0.102m

0.040m

0.062m

PAN I PAN II

BAFFLE

HEAT

Own design (2014)


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6. Summary

Proposed modifications

1st improvement: worse heat transfer to the first pot, no significant improvemnt of the second pot

2nd improvement: enlargment of the pot hole diameter is limited

3rd improvement: best potencial, baffle size must be carefully planned and tested many variables affect heat transfer in a stove

Zube (2010)


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7. Recommendations

More research on multipot ICS currently scarce literature

Peruvian regulation (2009) as model for neighbor countries (e.g. Bolivia): definition of temperature ranges to allow ICS certification

Field testing with a cook piece (Kitchen Performance Test)

Good practice measures: cut dry wood in small pieces and use lids

Decrease costs of the product without compromising its

quality access by means of microfinance mechanisms

Main objective of the ICS: guarantee a safe, affordable

and environmentally sustainable cooking process


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THANK YOU!


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Extras

MEI (2014)

Weekly income of the participants (February 2014)

0%

3%

0%

0%

33%

47%

14%

3%

Less than 100 PEN

101 - 200 PEN

201- 300 PEN

301 - 400 PEN

401 - 500 PEN

501 - 600 PEN

More than 601PEN

Unkwown/unsure

energetic optimization of an improved cooking stove … · alvarez p.h.j. estudio de cocinas...

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