Mechanical Engineering Commons^™

Photovoltaics: A Question And Answer Primer, Florida Solar Energy Center, Ingrid Melody

FSEC Energy Research Center®

Of all the solar energy technologies, photovoltaics (PV) show the greatest promise for worldwide acceptance and application. Their universal appeal lies in the fact that they generate electricity from the sun. Working photovoltaics have no moving parts, are relatively simple in design, need very little maintenance and are environmentally benign. They simply and silently produce electricity whenever they are exposed to light.

Passive Cooling Ideas For The Southeast, Florida Solar Energy Center, Chris Beck

FSEC Energy Research Center®

A passively cooled home is one which is kept relatively comfortable through natural means. Homeowners in the Southeast have been using passive building techniques in order to live more comfortably during hot, humid seasons since the early 1900's. The concept of designing for minimum use of artificial cooling and heating systems is not new, but with the advent of sophisticated mechanical air-conditioning and heating systems and the availability of inexpensive fossil fuels in the '40s and '50s, builders began bypassing passive techniques. Too many of today's homes are designed with more concern about accommodating a mechanical conditioning system than with …

Designing And Installing Commercial Solar Pool Heating Systems, Florida Solar Energy Center, Douglass E. Root

FSEC Energy Research Center®

Solar heating of swimming pools is an economically attractive utilization of Florida's abundant solar resource. The temperature requirement is lower than that of domestic or service water heating, lower than that for building heating and far lower than that for solar powered air conditioning. Florida's year-round mild and sunny climate allows swimming during much of the winter, so a properly heated pool is economically attractive.

A Checklist For Building An Energy Efficient Home In Florida, Florida Solar Energy Center, Michael Houston

FSEC Energy Research Center®

To design and build an energy-efficient home in Florida, seriously consider each of the steps listed here. Some are common sense, most are relatively inexpensive, and all add up to much lower energy bills. In fact, by following this checklist, you could expect to be very comfortable year round in your home and save about 30%-50% on your utility bills.

Photovoltaic Cells: Common Power Source For Tomorrow?, Florida Solar Energy Center, Arthur Litka

FSEC Energy Research Center®

The word "photovoltaic" combines the scientific terms "photo", meaning light, and "voltaic", meaning voltage. Together, the terms mean voltage generated by light energy. Specially treated silicon, or another substance, is manufactured in such a way that when light strikes it electricity is produced. The cells have no moving parts, and they are durable. They are commonly called solar cells.

Passive Cooling And Human Comfort, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

Comfort within buildings is primarily controlled by four major factors: air temperature, mean radiant temperature, humidity and airflow. Each can have a dominating effect. Their effects are not necessarily additive and practically never linear. There are, additionally, other factors which affect comfort including clothing, activity level and climatization. Some psychological triggers, such as certain colors, also seem to affect comfort, and "state of mind" can have major effects on individual comfort sensations. Comfort zones, therefore, are very generally defined as the zone in which 80 percent of the population will experience the sensation of thermal comfort.

Concepts In Passive Design #2: Devices For East And West Shading, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

A major source of heat in buildings is direct solar radiation through east and west windows--welcome heat energy in cold weather, but a summertime problem. Since Florida has such a long cooling season and generally a short heating season, it is especially important to protect east and west walls, windows, and sliding glass doors from the summer sun while allowing adequate light to enter the building year-round. From a lighting standpoint, natural daylight is on the whole quite good but it can produce unwanted heat and visual glare if not properly controlled.

Concepts In Passive Design #3 Passive Cooling Categorizations, Florida Solar Energy Center

FSEC Energy Research Center®

Editor's Note: While passive solar heating is relatively well evolved, passive cooling is only on the threshold of development, and many of its terms are new to the practicing professional. At the Fourth Annual Passive Cooling Conference this problem was addressed by William W. Holmes of the University of Nebraska with the presentation of a 10-point categorization of cooling techniques. We are indebted to Mr. Holmes for this contribution to the emerging field of passive cooling and present it here as a point of departure and working vocabulary for the design professional.

Concepts In Passive Design #1 Roof Overhangs, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

A major source of heat in buildings is direct solar radiation through windows--welcome in cold weather, but a problem in hot weather. Since Florida has such a lengthy cooling season, it is most important to protect windows from the sun; however, there are times between November and March when some heat is needed. Fortunately, the change in the sun's path from summer to winter is such that a properly designed roof overhang can protect south-facing windows from the high summer sun, yet allow the lower winter sun to come in.

A Cavity Absorber For A Focusing Solar Collector, Andrew W. Crapo

Retrospective Theses and Dissertations

The concept of a cavity absorber for use with a focusing parabolic trough is developed in this paper. A mathematical model is formulated and used to compare different absorber geometries. Limitations of the model are discussed and within the range of materials and fabrication methods available, the choice of a cylindrical cavity is substantiated. Relative sizes of the gap and cylinder are chosen for a given mirror arc length, focal length, and alignment error. The model is used to optimize these parameters and predict absorber and collector efficiency. The processes of building and testing the absorber are detailed, and test …

Thermosiphon System, Florida Solar Energy Center

FSEC Energy Research Center®

In a THERMOSIPHON SYSTEM, cold water from the bottom of the elevated storage tank flows to the lowest point in the system (which is the bottom of the solar collector).

As it is warmed it becomes less dense and flows up to a side port near, but not at, the top of the storage tank. If the tank is about two feet above the top of the collector, the system will not back-siphon at night. If back-siphoning were to occur, the warm water would be cooled during its passage through the dormant collector. Thermosiphoning systems have no moving parts and …

A Passive Cooler For A Humid Climate, Steven Gilbert Ring

Retrospective Theses and Dissertations

This paper examine a passive cooling system for a humid climate. This system will be divided into two parts, a radiative system and an evaporative system combined into a roof pond system. Performance of the radiative system will be enhanced through the use of a selective cover which will make use of an atmospheric window between 8 and 13um. An attempt will also be made to thermally isolate the radiative system from convective gains with the evaporative system. The evaporative system will consist of a water, solvent and dye layer over the selective cover of the radiative system. The performance …

The Design And Analysis Of A Unique Broadband Underwater Acoustic Source, Allan Mark Young

Retrospective Theses and Dissertations

Requirements exist for a unique type of underwater acoustic source. The transducer is in the form of a linear array of discrete elements and is required to have a constants transmitting voltage response and carefully controlled directivity characteristics over a two octave bandwidth. A generalized model of a linear array of cylindrical piezoelectric ceramic acoustic radiators is developed and applied to the design of a prototype which operates over approximately one half of the required bandwidth. The prototype transducer was built and the measured results are compared with those predicted by the model. Recommendations are made for improving the performance …

An Investigation Of A Variable Geometry Diffuser For Ftu's Four Inch Supersonic Wind Tunnel, William Robert Freed

Retrospective Theses and Dissertations

The primary object of the investigation reported in this paper was to obtain information that would aid in the design of a more efficient diffuser for FTU's tunnel, and thus increase the run time. Presently FTU's four inch supersonic wind tunnel uses a constant area, normal shock, diffuser to recover the fluid pressure after the test section. Also, FTU's tunnel is of the intermittent blowdown type, which provides only a relatively short test time before the storage pressure decreases to a limiting value at which flow in the test section ceases to be supersonic. The use of a constant area …