Characteristics of water - John White - EMS water.pdf · Characteristics of water Boiling point ... passing out of the combustion chamber ... Microsoft PowerPoint - hot water.ppt

Characteristics of waterBoiling point – 212F @ sea level, higher altitudes?

Freezing point - 32F

Specific heat – 1.0 Ammonia has highest

ice and steam SH = .5

Specific weight 1.0

Latent heat of fusion – 144 BTU/lb.

Latent heat of vaporization – 970 BTU/lb.

PH – 7 neutral – (less is acid more is base)

Mpemba (IM PEM BAH)effect

Altitude affects boiling point

Altitude (ft) Altitude (m) Pressure (mm-Hg) Temp. °F Temp. °C

0 0 759.85 212.0 100.0500 152.4 746.54 211.1 99.50

1000 304.8 733.46 210.2 99.011500 457.2 720.60 209.3 98.522000 609.6 707.98 208.5 98.032500 762.0 695.57 207.6 97.543000 914.4 683.38 206.7 97.053500 1067 671.41 205.8 96.574000 1219 659.65 204.9 96.084500 1372 648.09 204.1 95.605000 1524 636.73 203.2 95.12

Specific weight of water = 1.0Aluminum 2.7

Copper 8.96

Iron 7.87

Lead 11.3

Brass 8.4

Magnesium 1.74

Zinc 7.14

Lead 11.3

Water 1.00

Ice 0.917

Specific weight of oils = .8 -.95

Temperature- t -(oF)

Density

- ρ -(slugs/ft3)

Specific Weight

- γ -(lb/ft3) (lb/gallon)

32 1.940 62.42 8.343640 1.940 62.43 8.345150 1.940 62.41 8.343060 1.938 62.37 8.337870 1.936 62.30 8.329080 1.934 62.22 8.317690 1.931 62.11 8.3077100 1.927 62 8.2877120 1.918 61.71 8.2498140 1.908 61.38 8.2048160 1.896 61 8.1537180 1.883 60.58 8.0969200 1.869 60.12 8.0351212 1.860 59.83 7.9957

Specific heat

Specific heat of water = 1

Material (cal/g °C) (J/kg K) (cal/g) (J/kg)

Aluminum 0.215 900 94.5 3.96x105

Copper 0.092 385 49.0 2.05x105

Iron 0.107 448 63.7 2.67x105

Lead 0.031 130 5.5 0.23x105

Brass 0.092 385 Unknown Unknown

Magnesium 0.245 1030 88.0 3.7x105

Zinc 0.093 390 27.0 1.1x105

Styrofoam 0.27 1131 Unknown Unknown

Air 0.240 1006 N/A N/A

Water 1.000 4190 N/A N/A

Ice 0.500 2095

BTU’s required to heat water

It takes 1 BTU to heat 1 pound of water 1 degree F

BTU’s = pounds X temp. diff.

Latent heat of fusion

Pounds x 144 BTU’s

Latent heat of vaporization

Pounds x 970 BTU’s

Heat 200 pounds of ice @ 20F tosteam @ 220F.

PH factor

Pure water = 7 (neutral)

Above 7 – alkaline, tends to scale

Below 6 – acidic, tends to corrode

Maintaining temperature below 160Ftends to inhibit scaling in an opensystem. A close system generally willnot scale at higher temperatures.

Mpemba effectDiscovered in 1969 by student in Tanzania, Africa

Hot water freezes before cold waterWHY?

1. Good conduction – no frost2. Convection currents more active and reduced

insulating ice.3. Evaporative effect4. Warm water has less gaseous impurities

GAMA

Gas Appliance Manufacturers Association

http://www.gamanet.org/

Operating cost

Step 1. BTU’s = Lbs X TD

Step 2 Fuel = BTU’sBTU per unit X EF

BTU’s per unit

Oil- 144,000 per gallon

Natural gas – 100,000 per therm or 100 cubic feet

LP gas – 94,000 per gallon

Electric – 3413 per KW

Water mixing formulas

What will temperature be if 60 gals @ 120 degrees are mixedwith 30 gals @ 60 degree

Temp = (Q1 X Temp1) + (Q2 x Temp2)/ (Temp2 + Temp1)

= (60 X 120F) + (30 X 60F) / (120F + 60F)

= (7200 + 1800) / 180

= 9000/180

= 112.5F

Water mixing formula 2

If the cold water is 60F and there is 40 gals of 140F wateravailable, how many gals can be produced @ 95F

Q1 = Q2 x TD tankTD desired

= 40 gals. X (140F-60F)95F – 60F

= 40 gals. X 80F35F

= 320035

= 91.4 gallons

What happens when we lower the temperature to 120F?

Recovery Rate

Burner capacity X efficiency

8.33 x temp. rise

Recovery RateA 40,000 BTUH WH, 80% efficient, is capable

of supplying ________ gallons per hour atan 80F temperature rise.

1. Determine net output

40,000 BTUH x .80 = 32,000 BTUH

2. Determine amount BTU’s needed to raiseone gallon 80F

8.33 X 80 = 666.4

3. Recovery rate = 32,000666.4

= 48 gals per hour

First hour rating

First hour rating = recovery rate + tank capacity

= 48 gals. + 40 gal. tank

= 88 gals.

Affect of GPM on temp rise

Temp. Rise = BTUH (output)GPM X 500

500 = 8.33lbs. X 60 min.

Converting metric to imperial

Gallons = liters3.79

Liters = gallons X 3.79

Converting Fahrenheit to Celsiusand VS

F = (9/5 X C) + 32

C = 5/9 X (F – 32)

9’

40’

30’

Calculating volume

Volume of square or rectangular shaped building = area X height, or length X

Volume = length X width x height= 30’ X 40’ X 9’= 10,800 cubic feet

Volume of a triangular building = area of triangle X length or height

50’

6’

24’

Step 1. Area of triangle = length X height2

= 24’ X 6’2

= 72 sq. ft.

Step 2. Volume of triangle = area X length= 72 sq. ft. X 50’= 3600 cubic feet

Volume of a cylinder = Area of circle X length of cylinder

10’

30’

Step 1. Area of circle = π X Radius2 or πR2

= 3.14 X (5’ X 5’)= 3.14 X 25 square feet= 78.5 square feet

Step 2. Volume of cylinder = area of circle X length of cylinder= 78.5 square feet X 30’= 2355 cubic feet

Gallons = cubic feet / 7.48

Weight = cubic feet X 62.3 lbs.or

= gallons X 8.33 lbs.

Selecting a water heater

Conventional Storage Water Heaters

Demand (Tankless or Instantaneous) WaterHeaters

Heat Pump Water Heaters

Solar Water Heaters

Tankless Coil and Indirect Water Heaters

Conventional Storage Water Heaters

Demand (Tankless or Instantaneous)Water Heaters

Heat Pump Water Heaters

Solar Water Heaters

Tankless Coil and Indirect Water Heaters

Metlund or Chilipepper system

Heat traps

FVIRFlammable vapor ignition resistance

•A device to prevent ignited vapors frompassing out of the combustion chamber

•A one way intake system to control themovement of makeup air into thecombustion chamber

•An inner door and burner assembly tocreate a sealed junction with thecombustion chamber, preventingcombustion air and flammable vaporsfrom entering the chamber through thefront of the water heater

FVIR- TroubleshootingFlammable vapor ignition resistance

1. The installation environment may be dirty.

2. Temperature conditions exceed the TCO switchcutoff limit. Temperatures exceed 115° F

3. The water heater may be starved for combustionair. Don’t forget an electric dryer, it also consumes air.

4. There may not be a draft at the water heater drafthood.

5. A flammable vapor incident has occurred.

N.C. Plumbing Code Chapter 5

Section 501- water heater must be set at 120F. If thewater heater is used for space heating it may be set above120F. If the temperature is above 140F a mastertempering valve must be installed. (ASSE 1017).

Customer may set temperature above 120F but no oneelse may

Section 502.5

Water heater source of ignition must be 18” abovegarage floor. Both fossil fuel and electric.

Exception: FVIR appliances

Mechanical Code Section 1002.2

Water heaters used for space heating must beapproved for such use.

Note: When replacing a water heater used forheating be sure to replace with same BTUHrating.

Gas pipe sizing

Natural gas

LP gas

Venting – single appliance

How house pressurization affectsgas flame

Tax credits for solar WH

Federal - 30% until 2016 – no limit

North Carolina – 35% - $1400 limit

Solar water heating

Solar constant =429.2 BTU’s per sq. ft.

170 – 300 Btuh’ per sq. ft. reach the earth

Three types of solar energy to be collected

Direct – 300 Btu/sq. ft.

Diffuse – 50 Btu/sq. ft.

Reflected – 60 Btu/sq. ft.

Insolation

Average KWH/sq. meter/ year

Collector orientation

Face TRUE south (15 degree variation)

Tilt angle = degree latitude - water heating only

Degree latitude plus 15 degrees - space heating

(10 degree variation acceptable)

Flat plate collector

Glazing selection

High shortwave transmittnace (.2 – 3.0 micrometers)

Low longwave transmitance (greater than 3.0micrometers)

Low absorbance at all wavelenghts

Excellent weatherabilty

Single vs Double Glazing

For water heating only single glazing is all that’sneeded in our area.

Areas of low insolation would benefit with doubleglazing

Absorber Plate

Black Paint

97% absorbtion

97% emisstivity

Selective Surface

95% absorbtion

9-12% emisstivity

vs

Collector sizing

20 square feet per person for first two

8 square feet each person thereafter (sun belt)

12-14 square foot per person(north)

Corrosion Control

Prevent direct connection of anodic and cathodicmetals or supply sacrificial anodes.

Corroded end (anodic)

Magnesium

Zinc

Aluminum

Carbon steel

Brass

Tin

Copper

Bronze

Stainless steel

Protected end(cathodic)

Storage tank sizing

1.5 gallons per square foot collector area.

2 gallons per square foot in very sunny areas

These rules of thumb will prevent overheating

Transfer FluidsWater

+ cheap, high heat content, safe

– freezes, suports galvanic corrosion, boils at lowtemperature, promotes scale formation

Water/Glycol

+ will not freeze above –35F, can handle corrosioninhibitors

- Must be replaced regularly, not stable at hightemperatures, boils slightly above water

Hydrocarbons

+ Low cost, no freezing problems, nontoxic

- breakdown at high temperatures (become acidic), thickenwhen cold causing pump overload.

Silicon Fluids

+ do not freeze, do not boil, do not corrode, will last LOS

- Initial cost

Controls

Pump sizingCollector loop

Determine the head +adjusted friction losses

Determine the GPM

water- GPM = sq.ft. collector X .015

Silicon - GPM = sq. ft. collector X .039

Storage loop

Use manufactures specs