Refrigerant Charging for an AC System

HVACR Technology Program

San Jacinto College – North Campus

5800 Uvalde

Houston, TX 77049

http://www.sanjac.edu

281-998-6150

The Team

• HVACR Club Members– Manuel Munoz– Jacob Hernandez– Larry Duff– Jim Mills– Keith Hardy– Carlos Silos– Miguel Escamilla

• Faculty Advisor:Ben Ficklin

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TEAM PHOTO

Special thanks to: All the HVACR faculty at San Jacinto College

Objective

Objective Perform refrigerant charging on an AC system from one location after a “one-time” instrumentation setup.

The ProblemResidential AC systems are usually “split” systems with one part of the system (evaporator coil, metering device, blower motor, and air distribution ductwork) inside the house and the other part (condenser, compressor, and condenser fan) outside the house. All parts of this system should be monitored during the refrigerant charging process to ensure exactness of the charge. Because there is usually only one technician performing the task, the technician must spend a great deal of time “roaming” between the various system components observing various measured values during the charging process. A simpler, less stressful, and less time consuming workflow is needed.

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Methodology

The “mock” residential “split” AC system– A complete AC system including system ductwork

The Instrumentation– An IPhone– Temperature (Dry Bulb and Wet Bulb), Voltage, Current, Pressure,

and Air Velocity metersThe Measurements

Indoor Temperature: Wet bulb/dry bulb return and supply airOutdoor Temperature: Ambient at condenserSuction line and liquid line temperaturesAir Velocity: Across the evaporatorPressure: Saturation at evaporator and condenserVoltage: Compressor motor, condenser fan motor, indoor blower motor,

control voltage transformerCurrent: Compressor motor, condenser fan motor, indoor blower motor

The Test Configuration View: 1. “San Jac Intro and Instrument Review” video

2. “One Realtime Display for all Meters”3. “Thermal Imager Demo”

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Results

• Currently, the process to set up the instrumentation to obtain Bluetooth connectivity with the IPhone only worked for a few simultaneously connected meters, not all of them.

• Without all of the needed meters reporting simultaneously, the inefficient workflow of the technician “roaming” around the “split” system to monitor measurements remained.

• Key Bluetooth-enabled instruments are not available for the AC charging process: air flow, wet bulb temperature, and pressure

• Difficulty in getting Bluetooth-enabled meters to “pair” with smart phones in a timely fashion as well as to remain “paired” is a “deal breaker”

• Post-processing of recorded data to customized forms and then to an online storage database is yet to be evaluated

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Impact & Recommendations

• Needed: More Bluetooth-enabled instrumentsWe need additional Bluetooth-enabled instrumentation to properly monitor the refrigerant charging process:

Airflow meterWet bulb temperature meterRefrigerant pressure meter

View: “Three Needed Meters”

• Needed: Easier “pairing” of Bluetooth-enabled instruments…Additional instruments would not “pair” if more than a few were already “paired”

• Get the largest viewable area “smart” phone…Typical viewable area not sufficient to view all meters simultaneously…at least not with current graphic renderings

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Lessons learned

• Patience: Wait (a long time) for Bluetooth meters to “pair” with smart phone• Large number of simultaneous meter readings requires a simpler, textual

display….not enough display “real estate” using current graphics

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