South Campus Chiller

Chilled water production is a critical component for providing comfortable work environments. As such, the South Campus Chiller Plant, located on the University of Idaho campus, is responsible for producing & delivering chilled water to UI facilities. The UI South Campus Chiller Plant project was created with twofold objectives: 1) To identify existing operating conditions and components from a thermodynamic point of view, and 2) Develop and validate a working math model using Engineering Equation Solver (EES). This project was successful in meeting these objectives while providing the following deliverables: 1) A validated math model for simulating various operating conditions, 2) A wiki-page for project learning, and 3) A performance calculator incorporating the math model into a meaningful and intuitive Excel-based tool for calculating chilled water production and associated costs at the SCCP operator’s discretion.

Background info about chiller
The South Campus Chiller Plant (SCCP) is a plant that removes heat from water via absorption refrigeration cycle. The chilled water is then circulated through heat exchangers to cool university of Idaho's equipment as required. The SCCP uses cooling towers to take the heat out of the water being sent out to campus. The cooling towers work by misting the warm water down through air. The amount of heat being pulled out of the water being misted down is affected by ambient temperature.

Existing P&ID
This is a simplified P&ID of what we were given. Instruments surrounding the Thermal Energy Storage tank and SMARDT chillers allowed us to model these sections in EES without any added instrumentation.

Components of the cycle

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Problem Definition
The UI campus uses the chiller plant to provide cooling by using the SCCP as a central generator for chilled water which is then piped throughout the buildings to air handling units. The piped water then serves individual tenant spaces, single floors, or several floors. The campus chiller has multiple benefits such as greater energy efficiency, better controllability, and longer life. It is also efficient in terms of space utilization within the building because multiple components don't need to be in the same space. Throughout the year, our team worked on improving the quality, productivity and efficiency of the SCCP. This was done through various methods of data collection and analysis. The data collected from the SCCP's current operating conditions suggest some areas of inefficiencies, leading to unnecessary operating costs.

Project Goals:

 * Specify, order, and install flow, pressure, and temperature sensors
 * Develop a working math model of the existing chiller system
 * Test math model against current operating conditions
 * Develop a control system solution strategy
 * Quick reference for plant efficiency's
 * Excel calculator for efficiency calculation

South Campus Chiller Specs:

 * 2,000,000 gal storage tank
 * Trending data for 50 thermodynamic states
 * HFC-134A Refrigerant
 * 500 Ton capacity(x2)
 * Evapco evaporators(x2)
 * 40 HP Armstrong Pumps(x2)
 * SMARDT chiller(x2)
 * ABB Variable Frequency Drive(x6)

Updated P&ID


From the existing P&ID we were able to make additions to the existing instrumentation, which is shown here. We added two flow meters, activated an existing flow meter, two pressure transducers, and three temperature/enthalpy sensors. This added instrumentation allowed us to have a fully defined thermodynamic cycle, which made it capable to produce a math model.

Data analysis
The data that we collected using the existing and added instrumentation was given to us in .csv format. This data is collected in ATS from each instrument in individual files. We took those individual files and combined them into an single excel file. Once everything was combined we were able to use conditional formatting to find alarm data and the operating stages of the plant. From this data we were able to input it into our EES model to produce graphs and get correlations in between our math model predictions and the actual running of the plant.

Thermodynamic Cycle
The figure above shows the thermodynamic cycle including all of the state points that we were able to develop using the P&ID's and general plant layout. We input the cycle into EES and were able to create a math model. This math model was comprised of a Fist Law and steady state analysis. Loop 1 of the model consists of the water flowing from the Cooling Towers to the chillers. Loop 2 deals with the vapor compression cycle used by the chillers, with the working fluid being R-134a. Loop 3 is where the cooling of the HVAC water takes place.

Document Archive

 * [[Media:Design_Review_Just_Chillin.pdf|Design Review]]


 * [[Media:Tech_Presentation_Just_Chillin.pdf|Technical Presentation]]


 * [[Media:Project_Poster_SCCP.pdf|Project Poster]]


 * [[Media:meeting_min.pdf|Meeting Minutes]]


 * [[Media:Final_Model.pdf|Math Model]]


 * [[Media:calculator_final.pdf|Excel Calculator]]