Print this page HVAC: Cool Thermal Storage
A. Bhatia, B.E.
Course Outline
Operating refrigeration
chillers at night and displacing energy use from peak (day time) to off-peak
periods when the energy is at a lower cost is the primary objective of Thermal
Energy Storage. As a proven technology, chilled water or ice thermal storage
systems supply the desired reliability for high air conditioning availability
during peak hours and can substantially cut operating costs and reduce capital
outlays when systems are suitably designed.
TES applications are numerous and include private industry, residential &
commercial complexes, universities & school campus, hospitals, hotels, other
government facilities, and district cooling utility systems (i.e., systems in
which a business operates a centralized chilled water plant and utilizes a distribution
network to sell chilled water to multiple cooling customer facilities).
This course is designed to meet the continuing professional development needs
of individuals operating in the field of HVAC, energy conservation, architecture,
environmentalists, campaigners and other professional engineers.
This course includes
a multiple-choice quiz at the end, which is designed to enhance the understanding
of the course materials.
Learning Objective
At the conclusion of this course, the student will:
- Be aware of the fundamentals of thermal energy storage
- Be aware of different types of systems and the operating strategies
- Be able to judge
and select the right project alternative.
Thermal storage
systems offer building owners the potential for substantial operating cost savings
by using off-peak electricity to produce chilled water or ice for use in cooling
during peak-hours. Load shifting is typically the main reason to install a TES
system. Cool storage systems can significantly cut operating costs by cooling
with cheaper off-peak energy, and reducing or eliminating on-peak demand charges.
In a TES system, a storage medium is chilled during periods of low cooling demand,
and the stored cooling is used later to meet air-conditioning load or process
cooling loads.
The system consists of a storage medium in a tank, a packaged chiller or built-up
refrigeration system, and interconnecting piping, pumps, and controls. The storage
medium is generally water, ice, or a phase-change material (sometimes called
a eutectic salt); it is typically chilled to lower temperatures than would be
required for direct cooling to keep the storage tank size within economic limits.
The course is divided into 5 sections:
PART I Overview of Thermal Energy Storage
PART II Chilled Water Thermal Energy Storage
PART III Ice Bank Thermal Energy Storage
PART IV Choosing the Right System
PART V District Cooling Systems
Course Content
The the course content is in a PDF file HVAC: Cool Thermal Storage. You need to open or download this document to study this course.
Course
Summary
Thermal Energy
Storage (TES) System is a technology which shifts electric load to off-peak
hours, which will not only significantly lower energy and demand charges during
the air conditioning season, but can also lower total energy usage (kWh) as
well.
When demand for electricity is low (at night) and less expensive to purchase,
conventional chillers or industrial-grade ice-making units produce and store
cold water or ice. This stored coolness is then used for space conditioning
during hot afternoon hours, using only circulating pumps and fan energy in the
process.
Thermal energy storage (TES) systems chill storage media such as water, ice,
or phase-change materials. Operating strategies are generally classified as
either full storage or partial storage, referring to the amount of cooling load
transferred from on peak to off-peak.
TES systems are applicable in most commercial and industrial facilities, but
certain criteria must be met for economic feasibility. Capital costs of TES
depend on the economy of scales. If carefully designed for new facility significant
first cost operating benefits could be achieved.
A TES system can be appropriate when
- Maximum cooling load significantly higher than average load
- High demand charges, and a significant differential between on-peak and off-peak rates
- Appropriate where chiller capacity is needed for an existing system, or where back-up or redundant cooling capacity is desirable or where electrical infrastructure is inadequate to match demands
TES systems may
also reduce energy consumption, depending on site-specific design, notably where
chillers can be operated at full load during the night. Favorable nighttime
operation and lowering the chilled water temperatures and cold air distribution
can achieve significant savings achieved in pumps and fans operations. Number
of other design options can make TES systems more energy efficient than non-storage
systems.
Related Reading
Six Ways to
Perform Economic Evaluation of Projects
When you decide to implement a Thermal Energy Storage System, you must take
into consideration all the fixed and variable costs. It is recommended to carefully
analyze the benefits and carry out the life cycle assessment before implementing.
A course titled 'Six ways to perform economic evaluation
of projects' provides techniques to carry out the financial analysis
of new or retrofitting projects. This is a generic 2-hour course recommended
for the project advisors, architects and project engineers.
Life Cycle Assessment
for Building Projects
HVAC system is a significant proportion of the overall building cost. Life cycle
assessment (LCA) is a decision making process that is applied to large scale
building projects for evaluating the appropriate selection. The LCA takes into
account all capital costs, recurring operation & maintenance (O&M) expenses,
replacement costs, energy, environment and the code issues for the life cycle
of equipment. The overview of life cycle assessment (LCA) is presented in a
course titled 'Life Cycle Assessment for Building Projects'.
This is a generic 2-hour course recommended for engineering and financial planners.
Once
you finish studying the
above course content,
you need to
take a quiz
to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.com or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
