Chapter 6-part 1 Passive Solar

• Incident Solar Radiation-Effects of Latitude and Season

• Solar Heating through Time

• Uses of Passive Solar Heating Today– Passive Solar Houses– Solar Hot Water Heaters

Energy in the News

US Renewable Energy Use

Share in 1999:How is this mixDifferent from thatIn DevelopingCountries?Brazil?India?Other?

Expected Growth in Renewables: Bush Admin. 2001 Report

Is this right, especially given the relative costs of different sources?

Renewables: Second Best Growth

Can nuclear continue to outstripRenewables, why or why not?

What is the growth rate of wind powerIn Europe?

Solar Radiation vs Infrared RadiationWhy do the sunAnd the earth emitDifferent types of radiation?

Why does the mix of radiation change from the top to the bottom of the atmosphere?

What is insolation?

What are absorption bands?What is albedo?What is the greenhouse effect?

Seasonal and Latitudinal Insolation Variations

Why does solar insolation atHigh latitudes decrease duringWinter months?

What happens between theTropics of Cancer andCapricorn?

Angle of Incidence of Solar Insolation

Why does the optimumAngle from horizontal forA solar panel vary with theSeason (at high latitudes)?

What happens nearThe equator?

Seasonal Sunrise and Sun Angle at 40°N

Why is this variationIn angle importantFor passive solar design?

What happens at theEquator?At South Pole station?

Insolation on a Solar Collector: 40°N

What season doesThe flat collectorGet the most insolation?

What season does theVertical collectorGet the most insolation?

What would this graphLook like near the equator?

Types of Solar Insolation

Physics of cloudCover: still notWell known

Big problem in Climate models

How does totalInsolationdepend on the Solar constant?(PrecambrianEquatorial Glaciations)

Types of Solar Insolation

DirectReflectedDiffuse

Where do you get the most reflected insolation, on landOr on the water? Why?

What type of weather gives you more diffuse insolation,Cloudy or clear? Why?

How much of the incident solar radiation reaches theEarths surface?

US Mean Annual Solar Insolation

Where is insolation greatest?

Where is insolationLeast?

What is the ratio ofThe greatest toLeast insolationIn the US?Is this surprising?

Solar Printing PressInvented by AugustMouchat: 1878A: Solar CollectorB: Steam EngineC: Water Tank

Printing Press turnedBy steam engine

Parabolic Solar Collector

How does using water as the working fluid limit the collectors efficiency?

If outside air is at293K, what is theTheoretical efficiency?

Solar Pot

Mouchots solar potCould boil 3 liters ofWater in 1.5 hours.

Based on your problemSet, about how long would itTake to just bring the waterTo 100°C?

Adams solar cooking pot

Where inThe developingWorld would thesePots be easiestFor people to accept?

Least easy to accept?(Think cuisineNot income levels)

Telkes Oven

Why can this solar ovenReach higher temperaturesThan the previous oven?

What features of passive solarDesign does it incorporateThat make it more efficient?

Solar Water Distiller

Research vessels get water from evaporators. Why is it so hard to distill water in the Red Sea? Why does the ship need to be movingTo distill water? (Dredging leg in the Red Sea.)

General Features of Solar Heating

What uses a fan:Active or passiveSolar heating Systems?

Flat Plate Solar Collector

How is thisSolar collectorlike a greenhouse?

Why should itAbsorb more heatThan a typicalGreenhouse (three reasons)

Types of Solar Flat Plate Collectors

Which types are mostLikely to be passive?

Why?

Active solar hot water systemWhy is active solar more common at high latitudes?

Types of Solar Collectors

Thermosiphon Hot Water Heater

Passive Solar System

Water Collection TankMust be above the solarCollector. Why?

Very popular in the Middle East.Why are these systemsImpractical at higherLatitudes?

Bread Box or Batch Water Heater

Hot water is removedWhenever tap is turned on.

Payback time: 5 to 10 years.

Very inexpensive forPreheating water.

Solar shower used in GulfWar: very similar.

Increasing Systems Energy Efficiency of Hot Water Systems

Reduce water temperature to 120°F (depends on dishwasher)

Insulate heater to R-19

Use low flow showerhead and aerators (payback time 1 year)Reduce use by 50%

Install a graywater system (illegal in some areas) Special detergents needed

Install a timer on water heater so is only on when being used.

Install a tankless water heater system (some use open flameBut so do gas driers).