Honeywell Inc

ABSTRACT:
This final report documents the results of Contract DEN 3-38, Active Heat Exchanger System Development for Latent Heat Thermal Energy Storage Systems. The project was sponsored by the U.S. Department of Energy/Division of Energy Storage Systems and managed by the National Aeronautics and Space Administration/Lewis Research Center. The overall project consisted of five tasks to select, design, fabricate, test and evaluate candidate active heat exchanger modules for future applications to solar and conventional utility power plants. Alternative mechanizations of active heat exchange concepts were analyzed for use with heat of fusion Phase Change Materials (PCMs) in the temperature range of 250° to 350°c. Twenty-six heat exchange concepts were reviewed, and eight were selected for detailed assessment. Two candidates were selected for small-scale experimentation: a coated tube and shell heat exchanger and a direct contact reflux boiler. A dilute eutectic mixture of sodium nitrate and sodium hydroxide was selected as the PCM from over 50 candidate inorganic salt mixtures. Based on a salt screening process, eight major component salts were selected initially for further evaluation. Using an economic assessment program coupling the candidate salt mixtures and heat exchange concepts, NaNo3, NaN02, and NaOH appeared to be the most attractive major components in the temperature range of 250° to 35o0c. The minor components, selected in similar fashion, were NaOH, NaOH, and NaNo3, respectively.… (altro)

ABSTRACT:
This topical report describes active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250°C - 350°C, using the heat of fusion of molten salts for storing thermal energy. It identifies over 25 novel techniques for active heat exchange thermal energy storage systems. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs.

A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. Comparison of these costs with current state-of-the-art systems should be avoided due to significant differences in developmental status. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out.

The study resulted in the selection of a shell and coated-tube heat exchanger concept and a direct contact-reflux boiler heat exchange concept. For the storage medium, a dilute eutectic mixture of 99 wt% NaN0 3 and 1 wt% NaOH is selected for use in experimenting with the selected heat exchanger concepts in subsequent tasks.… (altro)

ABSTRACT:
INTRODUCTION - From 9 January through 20 January 1978 Honeywell conducted a wind tunnel test on a 1/30 scale partial heliostat field. The heliostats were per Honeywell's design developed under the 10 megawatt central receiver pilot electrical power plant subsystem research experiment contract. Likewise the scaled section of the field geometry duplicated the proposed circular layout. Testing was conducted at the Georgia Institute of Technology's 9 foot subsonic tunnel.
The objective of the test was to ascertain from a qualitative standpoint the field effects upon wind loading within a heliostat field. To accomplish this, numerous pressure tap measurements at different heights and at different field positions were taken with varying wind speeds, fence designs, and heliostat gimbal orientations. The Department of Energy specified boundary layer profile was also scaled by 1/30 in order to simulate the total wind effects as accurately as possible taking into account the potentially severe scaling or Reynolds number effects at a 1/30 scale.
After initial model set-up within the tunnel and scaled boundary layer generated, 91 separate runs were accomplished. The results do demonstrate the high sensitivity of wind loading upon the collector field due to the actual heliostat orientation and fence geometry. Vertical pressure gradients within the model field and flow reentry angles provide a good qualitative feel as to the full scale environment that might be expected and point to the need for specific additional testing to further explore potentially dangerous conditions.… (altro)

ABSTRACT:
The principal objectives of this task were to:
• Collect solar energy data pertinent to the continental u. s.
• Calculate the direct normal radiation from available total
(direct + diffuse) radiation measurements using the method of Liu and Jordan; and draw contours of equal direct radiation intensity.
• Identify, from the radiation maps, geographic regions receiving the highest radiation at the surface.
• Collect and analyze climatic data applicable to the identified regions.
• Recommend, based on both solar energy and climatic criteria, one or two of these regions as the best general location(s) for a solar power plant. (A specific site will be selected in Task
1. 2 using as a basis the non-solar site selection criteria developed in Task 1. 1. 2. )… (altro)