چگونه گلخانه با سیستم خورشیدی بسازیم؟ (زبان اصلی)
Energy from the sun heats the earth’s surface, makes clouds and creates weather. Atmospheric greenhouse gases such as CO2 and clouds trap some of the outgoing energy like a great blanket. The greenhouse effect moderates temperatures and makes life possible on this small green planet. The threat of global warming may someday become a serious problem if the current trend of fossil fuel consumption continues.
In the last 300 years the concentrations of carbon dioxide alone has increased by more than 30%.Without adequate emission control policies and alternative energies to choose from this concentration will most likely double during this century. If the greenhouse effect continues to escalate many scientists believe we will reach a point of no return. High temperatures mean increased plant growth, more rain, more vegetable growth, more decay and more carbon dioxide. More carbon dioxide increases the greenhouse effect, the cycle continues and the planet "hot balls" into an inferno like Venus.
How can people prevent global warming?
The answer to this question is simple. All we have to do is stop consuming vast quantities of fossil fuels and start searching for renewable energy supplies. We need to explore alternative energy options such as wind ,water and solar energy. Of these options solar energy appears to have the greatest potential over the largest area. To avoid excessive global warming we can use the same principle that' s causing it. .That's right! The greenhouse effect is a fundamental method of trapping heat from the sun. High frequency radiation such as ultraviolet and visible light is allowed to pass through a glazing. Once the light is inside the greenhouse and it strikes a non reflective surface the high frequency radiation is transformed into a low frequency heat radiation that can not pass back out through the glazing. Heat is trapped.
A commercial greenhouse nursery is a great way to get plants off to an early start.
A solar greenhouse can also be used to start plants although it's primary function is to heat a house.
A solar greenhouse is specially designed for heat gain. The glazing is perpendicular to the angle of a winter sun. The upside-down funnel shape of the greenhouse concentrates hot air near the top flap. On a 20 F., windy, January day in Plattsburgh NY I measured temperatures in excess of 160 degrees F. at the solar greenhouse apex. Hot air is lighter than cold air so it naturally rises and pushes the top flap open. The cold air return flap is pushed open in a like manner. This allows cold air from the living space to be returned into the solar greenhouse for heating.
At night the solar greenhouse cools down so that cold greenhouse air attempts to enter the house through the bottom flaps. This reverse circulation is prevented by the simple plastic one way flaps.
The solar greenhouse is a good example of a passive application of the greenhouse effect.
Active solar energy systems also make use of the greenhouse effect.
Another good application would be the flat plate collector. Heat from the greenhouse effect is able to boil water inside a well constructed solar collector. If you don't believe me try it. Just click on the banner and learn how to build
How to Build a Solar
Hot Water System
Printing January, 2004
Sunny Future Press, Wantagh, NY
Copyright John Canivan 2002
ISBN 0-975498-0-2 $30
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means electronic or mechanical without the express permission of the publisher. How to Build a Solar Hot Water System is an easy to follow, step-by-step 87-page book with clarified theory and dozens of illustrations. It was written for anyone concerned about saving money, and our little blue-green planet. For more information log onto: www.JC-SolarHomes.com
MATERIALS for collectors
1.Two rolls of 50-foot 20” aluminum flashing
2.Four .060-inch thick 4X8 sheets of Kalwall from: www.solar-components.com
3.Twenty 1X4X8 pine with few or no knots
4.Four ½X4X8 CDX plywood
5.Four 1X4X8 sheet insulation R value 5 or better
6.Clear silicon caulking
7.Aluminum foil and some felt paper
8.One gallon of roofing tar
9.One gallon of oil base paint
10.Angle iron for mounting
11.Sixteen ¼ X 3 lag bolts, sixteen ¼ X 1½ inch machine bolts with nuts and washers
12. 1 ¼ inch and 2 inch drywall screws
13.One pound of 1½ inch galvanized nails with small heads
a.Eight 3/8 to ½ adaptors
b.Four ½ inch T’s
c.Two ½ X ½ X ¾ T’s
d.One ¾ inch T
e.Four ½ inch unions
f.Eight ½ inch elbows
g.One ¾ inch street elbow
h.One ¾ sweat to ¾ female pipe
i.One pressure relief valve
j.Four sixty foot rolls of 3/8 ID copper tubing
k.½ - inch rigid copper tubing type L
l.¾ - inch rigid copper tubing type L or M
m.Solder and flux
Table of Contents
Chapter I SOLAR HOT WATER SYSTEMS
Passive hot water 9
Active hot water 10
Heat transfer 11
Parallel flow 13
Serpentine flow 14
Side joined collectors 15-16
Top/bottom joined collectors 17-18
Chapter II ABSORBER PLATE CONSTRUCTION
Pounding jig construction instructions 22
Absorber plate construction instructions 23-27
Chapter III COLLECTOR BUILDING INSTRUCTIONS
Step 1. Cut framing boards 28
Step 2. Assemble frame 29
Step 3. Fasten collector bottom and sides 30
Step 4. Construct tube bending jig 31
Step 5. Bend copper tubing 32
Step 6. Install insulation 33
Step 7. Drill inlet, outlet and vent holes 34
Step 8. Install absorber plate 35
Step 9. Install serpentine tubing 35
Step 10. Install sweat union 38
Step 11. Cut serpentine tube supports 40
Step 12. Install tube supports 41
Step 13. Touch up 42
Step 14. Install Kalwall 42
Chapter IV COLLECTOR MOUNTING
Theory of orientation and pitch 44
Assembly of horizontal and vertical supports 45
Chapter V HOT WATER STORAGE
Thermodynamic theory 46
Multi tank theory 48
Heat exchange coil theory 49
Chapter VI HEAT STORAGE VAULT CONSTRUCTION
Step 1. Tank preparation 51
Step 2. 4X4 supports 51
Step 3. Bottom platform 51
Step 4. Placing tanks on platform 52
Step 5. Framing the storage vault 53
Step 6. Insulating the storage vault 54
Step 7. Installing sides 54
Step 8. Installing sheet insulation 55
Step 9. Making and installing the inner lid 55
Chapter VII HEAT EXCHANGE COILS
Inner lid construction and installation 63-64
Chapter VIII CIRCULATION AND VAULT PLUMBING
Mounting platform 66
Plumbing overview 67
Details of plumbing 68
Chapter IX COLLECTOR PLUMBING
Union T assembly 71
Main output junction assembly 72
Main input junction assembly 73
Chapter X THE SENSOR SYSTEM 74
Chapter XI FILLING AND DRAINING THE SYSTEM 75-76
Chapter XII OTHER SOLAR APPLICATIONS 77
Author’s Note 80
Experimental Heat Storage Vault 81-87
If you have $2000 (in 2002) and a few weeks of labor to invest this book could save you $50,000 or more in hot water and home heating costs. You folks with carpentry and plumbing skills have a definite advantage. This book is definitely for you. This book is also for anyone with a grasp of the English language, capable of or willing to learn carpentry and plumbing skills. A good solar heating system is not free. It seems like it should be; after all heat from the sun is free why isn’t the solar heating system? Fossil fuel contractors throw in oil burners for free when they sign you sign up for a five-year contract. Why doesn’t Mr. Sunshine give us the same deal? I guess Mr. Sunshine is just a mean old man.
We are all part of a vast, interdependent universe. Energy for life is our birthright like the air we breathe or the water we drink. Our sun is enough to sustain us, and still we burn the fluid remains of our ancestors to stay warm. Buckminster Fuller, who coined the saying “Doing more with less,” compared fossil fuel with the starter motor of an automobile. He believed that the modern technological world we live in was started with a little boost from fossil fuel consumption. Once started technology should free us from dependence on non-renewable energy. Our starter motors are growing weary. It’s time to start the motor of social harmony, get back to our roots and welcome in the “Solar Age”.
SOLAR ELECTRICITY The photovoltaic power industry has a long way to go before becoming a practical investment for the average consumer although some remote locations miles from the power grid find that it is more practical to install solar than have power lines run to their house. Government incentives and technological production breakthroughs are necessary before the photovoltaic industry blossoms. $5.00/watt is too much. When the price comes down to $1.00/ watt give me a call. A typical $40,000 residential investment would take about 40 years to reach payback. This is of course assuming that $40,000 has the same value today as it would have forty years from now. Solar Electricity is a beautiful thing, but for most of us the time is not right. We’ll have to wait a little longer until this growing technology becomes feasible.
SOLAR HEATING Solar heating is feasible today. The average American household consumes between 1000 and 2000 gallons of number two fuel oil per year. Efficient use of the sun’s energy could easily cut this consumption in half or eliminate it entirely. The heating of water is perhaps the easiest, most cost effective solar project a person can get involved with.
SOLAR HOT WATER SYSTEMS
What once was a luxury is now a necessity. Over 500,000,000 households have or would like to have running hot water. In 1970 a friend of mine left the civilized comforts of a New Jersey home to seek out and experience the free, wild wilderness of an Adirondack hilltop in upstate New York. Jake loved the country life and swore that he’d never leave his mountain retreat. He endured the cold winters without electricity and baseboard heating, but Jake still missed running hot water. When spring came he took a 300-foot coil of black plastic tubing and connected one end to a spring high up on the mountain. He draped the remainder of the 300-foot coil on his roof and spread it out to cover as much surface area as possible. For a $50 investment and one hour’s worth of labor Jake had himself a bona fide hot water shower. He made good use of it whenever the sun was high on the mountain. I used it a few times myself. It works. The roof might look a little funny and the hot water would sometimes run out sooner than you’d like, but it did work when the sun was shining. When the sun disappeared the shower would get very cold. Toward the end of summer water would freeze inside the plastic pipe when the spigot was turned off.
You might be interested in a simple system like this if you enjoy taking showers when the sun shines. If you desire a more sophisticated hot water system you’ll need to invest more time and more money. I will be discussing several solar hot water designs. If you live in a very warm sunny area a simple passive batch heater is probably all you’ll need. If you’re interested in an automatic system that works well in cold climates with a minimum amount of sunlight you’ll need an active array of flat plate collectors with a massive heat storage system. Parabolic-trough heat concentrating collectors work, however they are usually inefficient, expensive and impractical.
PASSIVE HOT WATER
BATCH HEATERS In gentle climates like coastal California or almost any place in Florida where freezing is a rare occurrence a simple passive batch heating system is all that’s necessary. The batch heater could be as simple as a water tank painted black. A more efficient system would enclose this black tank in an insulated box. Glass or some form of glazing would be installed at an angle perpendicular to the sun’s rays. This is a practical, cost effective passive solar hot water system, ideal for gentle climates. For more information about this system check out www.solarnet.org
ACTIVE HOT WATER
Active solar hot water systems are designed for those less gentle climates. Although they are a bit more complicated and require electricity to run a circulator pump, active solar hot water systems harvest a lot of energy and save you money.
How much money will they save me on my fuel bill?
Good question. The answer to this question will of course depend on:
2.The orientation of your roof.
3.The angle that you position your collectors
4.The number of collectors used
5.How well you insulate the ¾” heat transfer pipes
6.The size of your heat storage vault
7.The amount of insulation used on the heat storage vault
8.The amount of hot water used
You are avoiding my question.
OK It’s a fair question and I’m going to give you the best answer I can from data on my collector performance and other environmental data. For my four-collector system with a storage vault of four 55-gallon drums I estimate a $500 savings per year on Long Island.
How much will the electricity cost to harvest all this heat?
Between $10 and $20 per year.
HEAT TRANSFER THEORY
Before diving into the building plans for an active solar hot water system I’d like to discuss a few basic concepts regarding light, heat and heat transfer.
How does light make heat?
Most of the sun’s energy that makes the 93,000,000-mile journey is in the form of visible and ultraviolet light. Heat is produced when high frequency light is converted into low frequency infrared radiation. Ultraviolet and visible light easily passes through glass, however when they strike a darkened surface they are converted into long wave infrared radiation. The glass or special solar glazing traps these long waves. This is known as the greenhouse effect. CO2 is also capable of trapping long wave radiation. Small amounts of CO2 keep our planet nice and warm. Too much CO2 in the atmosphere may transform our forest into deserts. Is it not ironic that we are using the same effect to save the planet that is destroying the planet?
Now I understand the Greenhouse effect. Could you explain what heat is?
With pleasure. Heat is a measure of the average motion of molecules. When light strikes an object it causes the molecules to vibrate faster. Intense light can ignite a log or melt steel. The faster an object vibrates the hotter it becomes. It’s as simple as that.
OK I get it. Light causes molecules to move faster. So how do these fast moving light excited molecules get into my hot water system?
They don’t. If they did you would have a contaminated system and you’d get sick and die, because collector fluid usually contains antifreeze. The molecules that are excited by the sun never enter your domestic hot water. Only molecular movement is transferred in the double insulated flat plat plate collector system that I am proposing.
Wouldn’t it be easier to use plain old ground water for collector fluid than you wouldn’t need antifreeze?
In gentle climates perhaps, however if you travel north of Georgia the batch tank would loose too much heat in the evening to be practical. Under extreme conditions the water in the tank might even freeze. For cold climates it is always best to separate the heat collection area from the heat storage area.
How about that drain away system?
Good point. There is another type of system called the DRAIN BACK or DRAIN DOWN system that allows heated water to drain back into a holding tank when sensors indicate that no heat gain is possible. Some of these systems employ heat exchange tanks and some use the solar heated water directly. These systems do save that hot water in the pipes with a system of automatic valves and relays, but it is more complicated, more expensive and more prone to problems than the double insulated heat exchange system.
OK! You convinced me. Should I get my tools? I feel like hammering and drilling and sawing and screwing.
That’s good, but hold onto these feelings a bit longer. I want to be sure you understand a few things about fluid mechanics.
Forget it. I have a friend who is still baffled by the concept of fluid mechanics and he spent four years of intense study at R.P.I..
Come on, it will be fun. Think of it as plumbing 101.
That sounds less threatening. I’ll give it a try.
That’s the spirit. I’ll make this as painless as possible and even throw in a few pictures to liven things up a bit. On the following pages I wish to compare and contrast two types of flat plate collectors, the parallel and the serpentine. Since the parallel collector is the most popular commercially available system I’ll discuss this one first. Here is an example of a flat plate parallel pipe collector system:
FLOW RATE THEORY
PARALLEL FLOW DYNAMICS
This parallel collector is designed to transport collector fluid from the bottom of the collector to the top via a network of parallel pipes. Notice that the top and bottom pipes are larger than the vertical pipes. There is a reason for this.
Fluid mechanics favors an increased flow rate for the end pipes. This is because incoming fluid pressure is greatest at the base of the first pipe and outgoing fluid pressure is smallest at the top of last pipe. If the top and bottom pipes are large the pressure difference is moderated and the flow rate in each of the parallel pipes is more uniform. These collectors may be connected in series because the top and bottom distribution tubes are so large. It is unfortunate that the flow rate is minimal at the center of the collector where most of the heat is concentrated. Other problems associated with the parallel flow with collector include cost and leaks. Half inch and two inch copper tubing is expensive, not to mention the dozens of special T fittings and all that solder. One small, undetected leak on one of those T fittings could become catastrophic mess.
SERPENTINE FLOW DYNAMICS
The serpentine collector consists of one long continuous flexible tube so there is no problem with uniform flow rate. The size of this flexible tubing is an important consideration. Quarter inch copper tubing is inexpensive, however it restricts the flow rate too much. Half inch flexible tubing is difficult to bend and fairly expensive. 3/8 inch tubing is just right for the money. It has a reasonable flow capacity, low cost, and ease of fabrication. What more could one ask for?
The main problem with a serpentine collector is flow rate restriction. Even the larger half inch copper tubing restricts flow rate too much and puts an unnecessary burden on the circulator pump. Connecting the serpentine collectors in parallel alleviates this problem. A two-collector system works fine. A four-collector system works even better. It is very important to bend this 3/8 copper tubing carefully to avoid kinks. This will insure that the flow rate is uniform throughout the serpentine collector array hooked in parallel.