e5 = energy efficiency entropy efficacy exergy

copyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resale

energy ∑ efficiency ∑ entropy ∑ efficacy ∑ exergye5 =

ashrae southern alberta chapter meeting


one of the greatest sources

of untapped energy is in the

exergy we destroy.

exergy and its role in sustainability

copyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resalecopyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resale

copyright notice

portions of this presentation are copy written by others, acknowledgments, credits and

references as noted, please advise the authors of any unintentional omissions.

permission to use material has been granted by copyright holders to robert bean

and or www.healthyheating.com with restricted distribution agreements, thus

this material may not be made available from third party websites, nor copied nor

distributed in either paper or digital form without permission from the respective

copyright holders.this educational material was assembled and copy written © 2010 by robert bean, all world rights reserved.

materials are not for resale and provided “as is” - for “not for profit” educational purposes.

if you have had to purchase these materials please contact us.


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housekeeping

webwise for radiomicrosoft clip art microsoft clip art

terrierman's daily dose

fiction, fires, phones, and fixtures


is easier to read

THAN Capitalized Text

APOLOGIES to

pascal, fahrenheit et al


improving the

accuracy of statistics

won’t change how

the human race

behavescredit source: http://en.wikipedia.org/wiki/image:cannonball_stack_with_fcc_unit_cell.jpg

polishing the cannonball


by definition, sustainability is a branch of philosophy which

for our industry, corrals engineering principles which can be

used to define, guide and measure industry’s earth

stewardship. in practice, sustainability points out that the

earth is but one large neighborhood and asks,

“how much of the nonrenewable energy belonging to the

neighborhood are we entitled to use”?



the energy content of the universe is constant, just as its mass content is.

yet at times of crisis we are bombarded with speeches and articles on how to

“conserve” energy.

as engineers, we know that energy is already conserved.

what is not conserved is exergy, which is the useful

work potential of the energy.

once the exergy is wasted, it can never be recovered. when we use energy (to heat our homes, for example), we are not destroying any energy; we are merely

converting it to a less useful form, a form of less exergy.çengel, y.a., boles, m.a., thermodynamics: an engineering approach, 5th edition, new york, mcgraw-hill: 2006



photo figure credit: unhindered by talent


exergy ask

“why are we

generating

> 1500°C when we

need < 60°C”?


©2010 the shock doc show, photo by denyce weiler

from bean’s exergy

perspective

it’s equivalent to

putting a blow

torch to your skin




gulp #1 - have you considered that

college students graduating in the year

2035 were born this year and will likely

work and live in buildings built to

standards developed over 30 years ago



gulp #2 - our generation will leave our

grandchildren with 60+ year old inefficient e5

system, with unintended, undetermined and

potentially crippling consequences in the

speculative world of energy, economics and

politics


heat recovery ventilators, thermal solar systems, radiant heating, insulated

concrete walls, condensing appliances, electronic ignition, larsen truss walls

air tight drywall approach, saskatchewan research house, and the r-2000

housing program were all products introduced during the era of the 80’s nep


bean graduates in 1983 having studied the above energy

solutions…then witnessed 30 years of nothingness

ottawa

alberta



13,000,000+ existing

homes in canada

practically all are built to

conventional or older

standards considered

downgrades from

e- star, r2000 and nze



0

200

400

600

800

1000

1200

1400

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

total house built 1990 to 2008 = 10,478

source: improving energy performance in canada – report to parliament under the energy efficiency act for the fiscal year 2008-2009

number of r-2000 housing certifications, 1990 to 2008


reality states: if we believe

sustainability should be the norm –

then the free market gives

permission to downgrade

construction to building code stds.

= 30% to 40% less efficient

who wants the downgrade?what part of this do people not understand?



death in a

box (>25% window wall ratios)

hvac’s fault for poor

comfort and energy !@#$^

Original graphic courtesy of uponor, adapted by rbean



better than death in a box

are glass towers

constructed in cold

climates with cooling fins




source credit: schock ltd

cooling fins

are never a

good thing in

architecture


1 exajoule

1 j x 1018

160 million

barrels of oil

=

annual energy

consumption by

15 million avg.

cdn home

=

energy produced

by 1400 km2

solar cell

canada’s energy flow (ej, exajoule)


cooling tower – mother of all oxymoron's

energy is conserved (reversible)

exergy is destroyed (irreversible)

anything that generates entropy

always destroys exergy

exergy destruction is wasted work

or wasted potential for the

production of work.




same story (tons/capita) but with population perspective

copyright d. mackay 2009, sustainable energy — without the hot air


6,706m334m

do we really

believe the rest

of the world

should behave

as we do?go ahead take a

second to think

about it




sustainability

tactics



the royal australian institute of architects



three little pigscombustion

customizationcomplexity



1. more features isn't better, it's worse.

2. you can't make things easier by adding to them.

3. confusion is the ultimate deal-breaker.

4. style matters.

5. only features that provide a good user

experience will be used.

6. features requiring learning will only be adopted

by a small fraction of users

7. unused features are not only useless, they can

slow you down and diminish ease of use.

8. users do not want to think about technology.

9. forget about the killer feature.

10. less is difficult, that's why less is more

the best products need no instructions


complicated & expensive mechanical system that need food (fuel and power) and therapy (service &

maintenance) are unsustainable and become poor choices in the presence of pet rocks like natural

materials, high performance windows, insulation upgrades, and detailed /air barrier caulking applications.


insulation, caulking and high performance windows electrothermomechanical


sustainability can’t be complex

nor customized and must

minimize or eliminate

combustion and compression



e-x-e-r-g-y efficiency



use of high

quality energy

to do low

quality work.

example:

burning

natural gas for

space heating

matching quality

of energy to the

quality of work.

example:

geothermal for

space heating

results in less

losses due

entropy laws



sustainable design revolves around

low temperature heating

high temperature coolingminimal exergy destruction via minimization of

combustion and compression



Fig. 9 design graph for heating and cooling with floor and ceiling panels, panel heating and cooling 6.9, reprinted w

ith perm

ission, 2000 AS

HR

AE

Handbook-S

ystems and E

quipment, w

ww.ashrae.org

copyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resaleIllustration copyright © 2009, Robert Bean

w/ 10°F∆t, tr = 80°F – (10°F/2) = 75°F ≈ η% ≈ 97%




97% boiler efficiency!stellar performance by anyone's standard

meets the efficiency test

“take what you need but

use what you take”



butenergy efficiency

≠exergy efficiency



Exergy efficiency calculator – Natural gas condensing boiler with radiant floor heating

Item Units Value Units Value

Room temp enter °F 72 °C 22

Media supply temp enter °F 85 °C 29

Heat transfer enter Btu/hr 100000 kW 29

Space heating exergy load Btu/hr 2385 kW 1

Room temp °F 72 °C 22

Combustion temp. enter °F 2800 °C 1538

Heat transfer Btu/hr 100000 kW 29


Exergy efficiency 3% 3%


how complicated is

geothermal

shallow hole =

low pressure and cool

deeper hole =

high pressure and hotter

≈ 6,400km

≈4m

≈ 2,900km

≈10km

≈1km270 bar

15°c 7000°c870°c400°c55°c

50% of earth’s surface presents local climates capable of

conditioning building spaces for four to six months of the year. carnegie-mellon study, 2009


Chilean miners ≈ 35°c (95°f)

@ 700 m (.43 miles)

shallower than oil/gas drilling in Alberta



Solar & Geothermal

A



Exergy efficiency calculator – Geothermal with radiant floor heating

Item Units Value Units Value

Room temp enter °F 72 °C 22

Media supply temp enter °F 85 °C 29

Heat transfer enter Btu/hr 100000 kW 29


Room temp °F 72 °C 22

Ground temp @700m depth enter °F 95 °C 35

Heat transfer Btu/hr 100000 kW 29


Exergy efficiency 58% 58%


Utilizationefficiency

energy exergy

Electricity generation 0.90‐0.95 0 .30

Industrial steam production 0.85 0.25

Fluidized bed electricity generation 0.40‐0.45 0.40‐0.45

Transportation (diesel powered) 0.4 0 .10

Transportation (gasoline powered) 0.25 0 .10

Space heating or cooling 0.50‐0.80 0 .05

Domestic water heating 0.50‐0.70 0 .05

Incandescent light bulb 0.05 0 .05



recommended studies

energy and exergy performance

of residential heating systems

with

separate mechanical ventilationRadu Zmeureanu, Xin Yu Wu

Center for Building Studies, Department of Building, Civil

and Environmental Engineering, Concordia University



exhaust airsupply air

reheat coil

radiant panel

heating

dwh preheat

dhw indirect

dwh

boiler

heatpump

ground loopearth loop mua

exhaust air

HRVF1

F2

QL

To

Ti

Etube

P1

P3

Wcomp

Eg, boiler

Eunderground

P2

F1

F2

P1

P2

P3

Wcomp

Ep,psupplied

Powerplant

dcw

exhaust airsupply air

reheat coil

radiant panel

heating

dwh preheat

dhw indirect

dwh

boiler

heatpump

ground loopearth loop mua

exhaust air

HRVF1

F2

QL

To

Ti

Etube

P1

P3

Wcomp

Eg, boiler

Eunderground

P2

F1

F2

P1

P2

P3

Wcomp

Ep,psupplied

Powerplant

dcw



selected residential hvac–dhw systems

system heating ventilation dhw

no. 1 electric baseboard heaters

none

electric water heater

no. 2 radiators with gas‐fired boiler heat exchanger with gas‐fired boiler

no. 3 radiant floor heating with gshp gshp and electric water heater

no. 4 electric baseboard heaters electric air heater electric water heater

no. 5 electric baseboard heaters electric air heater, and air‐to‐air heat exchanger electric water heater

no. 6 electric baseboard heaterselectric air heater, air‐to‐air heat exchanger and earth

tube heat exchangerelectric water heater

no. 7 radiators with gas‐fired boiler

hot water air heater, air‐to‐air heat exchanger and earth tube heat exchanger

heat exchanger with gas‐fired boiler

no. 8 radiant floor heating with gshp hot water heater and electric water heater

no. 9 radiant floor heating with gshp gshp and gas‐fired water heater

Source: Zmeureanu, R., Yu Wu, X., Energy and exergy performance of residential heating systems with separate mechanical ventilation, Energy 32:187–195, 2007



input values of some parameters used in simulations

items parameters input values

house

indoor design air temperature (tint) 21°C

floor heated area 310m2

room height 2.8m

ventilation systems

ventilation air change rate 0.3 ach

heat recovery efficiency of the air‐to‐air heat exchanger 60%

length of the earth tube exchanger 10m

cross‐section of the earth tube heat exchanger 0.25m x 0.25m






heating systems

energy efficiency of gas‐fired boiler 75%

temperature of flue gases from the gas‐fired boiler 230 °C

flame temperature 1927 °C

temperature of water for gas‐fired boiler 90 °C/70 °C

temperature of water for radiant floor 35 °C/30°C

temperature of water for radiators 90 °C/70 °C

temperature of refrigerant leaving condenser 40 °C

temperature of refrigerant leaving evaporator 3 °C

refrigerant used with gshp r134a

ground temperature 8 °C






dhw systems

design mass flow rate of dhw 0.0105 kg/s

temperature of dhw leaving the storage tank (tw,out) 60 °C

temperature of cold water from the city line (tcity) 8°C

energy efficiency of power plants

hydro power 80%

natural gas 43.1%

oil 33%

nuclear 30%




Nomenclature Subscripts

C, specific heat (kJ/kg K) a , air w water

CAP, capacity (kW) air,in, air entering the air‐to‐air heat exchanger w,1 water from condenser or boiler

COP, Coefficient of Performance air,out, air leaving the air‐to‐air heat exchanger w,2 domestic hot water

E, rate of energy (kW) de, destruction w,floor water in the radiant heating floor

EIR, electric input ratio (—) gen, total, total generatedw,in,floor water entering the radiant heating floorEq-GHG, equivalent greenhouse

gas emissions (ton/yr)int, interior air

Ex, rate of exergy (kW) city, water from city supply line w,out water leaving the DHW tank

M, mass flow rate (kg/s) exh,in, air leaving the house and entering the air‐to‐air heat exchanger

w,gl water entering the underground heat exchangerPLR part‐load ratio (—)

Q, thermal load (kW) out, outdoor air w,out,floor water leaving the radiant heating floorS, entropy (kWh/K) r, refrigerant

S, specific entropy (kJ/kg K) ref, reference state

T, temperature (°C) trans, transmission

TK, absolute temperature (K) vent, ventilation

Greek symbolsα, contribution to energy generation (—)

η2 second law efficiency (%) ηi efficiency of power generating plant (%)




Coefficient of performance of the system COP = Euseful/Esupply

Useful energy Euseful = Eheating + Event + EDHW

Energy for heating Eheating = Qspace

Energy for ventilation Event = mvent ∏ ca ∏ (Tint – Tout)

Sensible heat recovery efficiency of the air‐to‐air ηHE = (Tair,out – Tair,in ) / (Texh,in – Tair,in)

Energy for DHW EDHW = mw ∏ cw ∏ (Tw,out – Tcity)

Energy supply Esupply = Eprimary,plant + Egas,house

Primary energy use Eprimary,plant = Eelec,house / ηtrans ∏ ∑αi/ηi

Electric load of the house Eelec,house = Ecompressor + Epumps + Efans




Electric demand of compressor Ecompressor = CAPdesign ∏ EIR ∏ FRAC

Electric input ratio EIR = (0.11 + 0.89 ∏ PLR) / COPdesign

Chiller part‐load ratio PLR = Qload / CAPdesign

Nominal chiller capacity CAPdesign = 3.103+0.428 ∏ Tw,gl + 3.651 ∏ mw,gl

Nominal COP of chiller COPdesign = 2.94 + 0.031 ∏ Tw,gl + 0.191 ∏ mw,gl

Exergy efficiency of the system ηx = (1 - Exde/Exsupply) ∑ 100

Exergy destruction Exde = TKref ∏ Sgen,total

Total entropy generation Sgen,total = Sheating + Svent + SDWH + Strans + Splant

Entropy generation in heating system Sheating = Sfloor + SGSHP + Spumps




Entropy generation in GSHP SGSHP = Scompressor + Sevaporator + Scondenser + Svalve

Entropy generation in evaporator Sevaporator = mr ∏ ∆sr + mw ∏ ∆sw

Entropy generation in radiant floor Sfloor = Qload/Tkint + mw,floor ∏ (sw,out,floor - sw,in,floor)

Entropy generation in ventilation system Svent = Sheater + Sfans

Entropy generation in DHW tank SDWH = mw,1 ∏ ∆sw,1 + mw,2 ∏ ∆sw,2

Exergy supply

Exsupply = ∑Qplant,i ∑ (1-TKref/TKflame) + Ehydro + Enuclear + Egas, house ∑ (1-TKref/TKflame)




Annual performance of selected residential HVAC–DHW systems under scenario no. 1 and reference temperature equal to hourly outdoor air temperature

System COP (—) η2 (%) Sgenerated (kWh/K) Quseful (kWh) Exdestroyed (kWh) Exsupply (kWh) Eq‐GHG emissions

(ton/yr)

No. 1 0.71 7 95.1 19555 25608 27539 0.2

No. 2 0.73 8.5 80.1 19555 21596 23608 4.8

No. 3 1.19 30.6 39.7 19555 10722 15441 0.1

No. 4 0.66 5.3 160.4 30343 43136 45550 0.4

No. 5 0.83 5.4 128.3 30343 34537 36525 0.3

No. 6 0.88 5.9 120.7 30343 32536 34568 0.3

No. 7 0.9 7.1 103.3 30343 27847 29974 4.8

No. 8 1.49 26.3 53.2 30343 14382 19519 0.2

No. 9 1.46 27.8 51.4 30343 13889 19224 1.3




Annual performance of selected residential HVAC–DHW systems under scenario no. 1 and reference temperature equal to hourly outdoor air temperature

System COP (—) η2 (%) Sgenerated (kWh/K) Quseful (kWh) Exdestroyed (kWh) Exsupply (kWh) Eq‐GHG emissions

(ton/yr)

No. 1 electric baseboard heaters, electric water heater 0.2

No. 2 radiators with gas‐fired boiler, heat exchanger with gas‐fired boiler 4.8

No. 3 rfh w/ gshp, no ventilation, electric water heater 0.1

No. 4 electric baseboard heaters, electric air heater, electric water heater 0.4

No. 5 electric baseboard heaters, electric air heater, and air‐to‐air heat exchanger, electric water heater 0.3

No. 6 electric baseboard htrs, electric air heater, air‐to‐air heat exch. and earth tube heat exchanger, electric water htr 0.3

No. 7 radiators w/gas‐fired boiler, hw air htr, air‐to‐air heat exch., earth tube heat exch., heat exch. with gas‐fired boiler 4.8

No. 8 rfh w/ gshp, hot water air heater, air‐to‐air heat exchanger and earth tube heat exchanger, elec water heater 0.2

No. 9 rfh w/ gshp, hot water air heater, air‐to‐air heat exchanger and earth tube heat exchanger, gas water heater 1.3




unsustainablesustainable

exergy and its role in sustainabilitybu

ildin

g pe

rform

ance

conservation

and less

exergy

destruction

consumption

and more

exergy

destruction


≈ 75°F - 85°F

@ 40% rh

is the sweet

spot for

everything




change! haha! try harder bubba!



department of energynational renewable energy labresearch support facilities (rsf)net zero energy

photo credit/original source: bob fox, haselden construction, john andary, pe, leed ap, stantec, tom hootman, aia, leed ap, rnl


conclusion



sustainability requires us to put into

practice our knowledge

of e5

energy ∑ efficiency ∑ entropy ∑ efficacy ∑ exergy




original photo © 2009, kerrysphotos , adapted image © robert bean

energy ∑ entropy ∑ efficiency ∑

efficacy ∑ exergy

+

green principles

=

sustainability

copyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resalecopyright © 2009, robert bean and content providers –all rights reserved - for continuing education only - not for resale

portions of this presentation are copy written by others, acknowledgments, credits and

references as noted, please advise the authors of any unintentional omissions.

permission to use material has been granted by copyright holders to robert bean

and or www.healthyheating.com with restricted distribution agreements, thus

this material may not be made available from third party websites, nor copied nor

distributed in either paper or digital form without permission from the respective

copyright holders.this educational material was assembled and copy written © 2010 by robert bean, all world rights reserved.

materials are not for resale and provided “as is” - for “not for profit” educational purposes.

if you have had to purchase these materials please contact us.

copyright notice


energy ∑ efficiency ∑ entropy ∑ efficacy ∑ exergye5 =

ashrae southern alberta chapter meeting

e5 = energy efficiency entropy efficacy exergy

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