1. Sustainable Energy Systems Engineering Peter Gevorkian Ch 8: Passive Solar Heating Technology Brevard Community College ETP1401 Bruce Hesher

2. Passive Solar (also called solar thermal) heating refers to exposing water or other fluids directly to the sun in order to heat them, instead of using electricity or other fuels. Passive Solar (also called solar thermal) heating refers to exposing water or other fluids directly to the sun in order to heat them, instead of using electricity or other fuels. Efficiencies can be higher (up to 70%) than using other technologies that have more conversion steps. Efficiencies can be higher (up to 70%) than using other technologies that have more conversion steps. This is the “low hanging fruit” of the renewable energy market. While photovoltaic systems are gaining traction, most solar installations, as of 2011, are solar water heating systems. Why? Paybacks are shorter (3-5 versus 8-10 years) and initial investment is lower. This is the “low hanging fruit” of the renewable energy market. While photovoltaic systems are gaining traction, most solar installations, as of 2011, are solar water heating systems. Why? Paybacks are shorter (3-5 versus 8-10 years) and initial investment is lower.

3. Solar Thermal Uses Solar Thermal Technology can be used for many purposes including: Solar Thermal Technology can be used for many purposes including: Solar Water Heating (domestic and commercial) Solar Water Heating (domestic and commercial) Swimming Pool Heating Swimming Pool Heating Space Heating Space Heating Note: the word “passive” has multiple meaning in solar thermal systems. It can mean using the suns energy to heat fluids directly, and it can mean using the heat from the sun to cause the fluids to circulate without any other energy input (no pumps).

4. Passive Solar Water Heating Solar Water Heating (SWH) is mature technology that reduces the need to buy energy to heat water. After weatherization and conservation SWH is usually the next thing to consider. As with most renewable energy technologies, SWH has high up front costs and low cost of operation. The on equipment that As with most renewable energy technologies, SWH has high up front costs and low cost of operation. The payback is 3-5 years on equipment that lasts over 20 years.

5. Flat Plate Collectors Flat plate collectors are made of copper pipe and painted black. They are in sealed boxes that let light in and prevent heat loss. They are much more efficient at capturing the suns energy than solar electric modules. 60-70% versus 12- 22%! They are placed on the roof in a location with good southern exposure. They are placed on the roof in a location with good southern exposure.

6. SWH System Diagram Solar water heating systems are more complex than traditional electric or gas tanks but use free fuel! 25-30% About 25-30% of the typical electric bill is water heating. SWH systems cost about $3-4k. The quality of the installation makes a big difference!

7. SWH System Types There are many different designs for different climates. There are many different designs for different climates. A “direct” a.k.a. “open Loop” system sends the potable water through the collector. An “indirect” a.k.a. “closed loop” system uses a heat exchange fluid (usually propylene glycol) in the collector and a heat exchanger. A “passive” system uses the heat of the water to cause it to circulate. An “active” system uses a pump(s). The pump may be powered by a wall socket or by a 10-20W solar module.

8. System Types Many different system designs are possible depending on climate, capacity, performance, price and Etc. In Florida direct, active systems are common. The BCC course ETP1420 Solar Thermal Systems covers SWH. Closed loop Closed loop systems with propylene glycol in the collector loop are recommended for areas where freezing is possible. Thermo-siphon Thermo-siphon systems are inexpensive and reliable because they have few moving parts. But they require the storage tank to be above the collector Integrated Collector Systems Integrated Collector Systems “ICS” are only used where there is no chance of freezing.

9. Solar Pool Heating Heat collectors made of black plastic tubing panels placed on roof and in the return line from filter to pool add energy (heat) to the water. A solar blanket on top of the pool cuts evaporative heat loss which accounts for over 70% of the total heat losses. A solar blanket on top of the pool cuts evaporative heat loss which accounts for over 70% of the total heat losses.

10. Solar Space Heating See http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm# Passive http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm# Passive http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm# Passive

11. Concentrating Solar Power CSP p222 CSP is used in commercial setting to generate electricity. A fluid usually oil is heated then run through a heat exchanger to turn water into steam to run a generator. CSP is used in commercial setting to generate electricity. A fluid usually oil is heated then run through a heat exchanger to turn water into steam to run a generator. Another method is to reflect sunlight onto a boiler and heat it directly.

12. Solar Cookers Parabolic dish solar cookers are effective ovens on sunny days. Parabolic dish solar cookers are effective ovens on sunny days. They can reach temperatures over 400°F ! They can reach temperatures over 400°F ! They fold down for easy storage or transportation. They fold down for easy storage or transportation.

13. Solar Cooling and Air Conditioning. Cold is the absence of heat. The science that deals with heat is thermodynamics. It has 2 basic laws: 1) Conservation of energy: Energy can not be created or destroyed. However it can be converted from one form to another. 2) Energy is always transferred from a higher state to a lower one. There are 3 ways heat can transfer: Radiation: ex. Sun to Earth Radiation: ex. Sun to Earth Conduction: Heat transfer by physical contact. Conduction: Heat transfer by physical contact. Convection: flow of heat between air, gas, liquid, or fluids. Convection: flow of heat between air, gas, liquid, or fluids.

14. Cooling Technologies p228 There are 2 types of refrigeration technologies in use electric vapor-compression (freon gas) and heat driven absorption cooling. There are 2 types of refrigeration technologies in use electric vapor-compression (freon gas) and heat driven absorption cooling. Absorption coolers are operated by steam, hot water, fossil fuels or a combination. There are 2 types of absorption chillers that have been used for about 100 years: Absorption coolers are operated by steam, hot water, fossil fuels or a combination. There are 2 types of absorption chillers that have been used for about 100 years: 1) Lithium Bromide LiBr: Uses LiBr as the energy conversion medium and water as a refrigerant. Can get down to about 40°F. 1) Lithium Bromide LiBr: Uses LiBr as the energy conversion medium and water as a refrigerant. Can get down to about 40°F. 2) Amonia chillers use ammonia as the energy conversion media and a mix of ammonia and water as the refrigerant. They can get down to about 20°F. 2) Amonia chillers use ammonia as the energy conversion media and a mix of ammonia and water as the refrigerant. They can get down to about 20°F.

15. States of Matter Most substances can exist as vapor, liquid, or a solid depending on temperature. When the substance changes state heat is transferred. When liquids become gases heat is absorbed (they get cold). When gases are compressed into liquids heat is given off. This is why the compressor under a refrigerator gets warm and has a cooling fan.

16. Coefficient of Performance “COP “ p228 The efficiency of an air conditioning systems is defined by the “COP” as the ratio of cooling energy to the energy supplied to the unit. The efficiency of an air conditioning systems is defined by the “COP” as the ratio of cooling energy to the energy supplied to the unit. A ton of cooling energy is 12,000 British thermal Units (btu’s) per hour. A cooling ton is also equal to 3514 Watts of electric power. A ton of cooling energy is 12,000 British thermal Units (btu’s) per hour. A cooling ton is also equal to 3514 Watts of electric power. A one ton air conditioning unit that consumes 1500W of electric power would have a COP of 3514W/1500W or 2.343. A one ton air conditioning unit that consumes 1500W of electric power would have a COP of 3514W/1500W or 2.343.

17. Simplified diagram of a single effect absorption cycle Efficiency and lower operating costs are achieved through the use of a pump rather than a compressor and a heat exchanger to recover and supply heat to the generator. Efficiency and lower operating costs are achieved through the use of a pump rather than a compressor and a heat exchanger to recover and supply heat to the generator. Although the process is similar to conventional electric vapor compression systems, absorption cooling substitutes a generator and absorber, called a thermal compressor, for an electric compressor. Although the process is similar to conventional electric vapor compression systems, absorption cooling substitutes a generator and absorber, called a thermal compressor, for an electric compressor. See http://www.gasairconditioning.org/absorption_how_it_works.htmhttp://www.gasairconditioning.org/absorption_how_it_works.htm

18. Direct Solar Power Generation Solargenix Energy has developed a Concentrating Solar Power (CSP) generation facility in Red Rock Arizona that make about 1MW of power. Solargenix Energy has developed a Concentrating Solar Power (CSP) generation facility in Red Rock Arizona that make about 1MW of power. Solargenix has advanced concentrating trough technology in recent years: Solargenix has advanced concentrating trough technology in recent years: See NREL: Solargenix white paper NREL: Solargenix white paperNREL: Solargenix white paper

19. Innovations in Passive Solar Power Technology p230 Someone is always working on a new idea. Some of them are good, some are not. Some make it to the market place some don’t. The text presents some ideas. Someone is always working on a new idea. Some of them are good, some are not. Some make it to the market place some don’t. The text presents some ideas. Sunflower 250: A solar PV system with tracking and concentrating. Stirling Engine Stirling Engine Sunflower: A system with multiple mirrors concentrating heat to run a Stirling engine. Stirling Engine SunPod A PV system that uses a Fresnel lens to concentrate solar power.