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COMPRESSOR
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NOISE OF CHARGING STATE
Objective
- Test if the compressor (with the pump if they are running at the same time) noise is below 85dB. As discussed in Specification Notes, OSHA has set regulations within workspaces requiring employees to wear some sort of ear protection if they are exposed to a noise level of 85dB for a period of 8 hours. Although we will not be running the compressor for a period of time close to or longer than that duration, this is a good threshold to set.
Anticipated results
- Specification sheet provided by the manufacturer states that the expected sound level is 78 dB. Therefore we will anticipate the noise created by the compressor to be around that level.
Steps involved for experimentation
- Use an iphone dB measuring app and measure the dB levels once the compressor and pump are running simultaneously
Equipment that is required
- Iphone
- In-ear or over-ear noise protection
Safety Precautions
- Wear safety goggles to protect eyes once compressor is running and wear hearing protection
Anticipated time
- 5 min
Testing Date
- 4/4/22-4/9/22
2. MECHANICAL EFFICIENCY- COMPRESSOR
Objective
- Calculate the compressor’s mechanical efficiency.
Anticipated results
- We expect the compressor to have an efficiency of 10-20% based on our low fidelity modeling, but there is a chance that the actual efficiency is a lot lower. This is due to the fact that the compressor was designed for commercial use and high efficiency is ultimately not the manufacturer’s main desire. This was speculated from the output CFM and horsepower values obtained from the manufacturer spec sheet.
Steps involved for experimentation
- Calculation of mechanical efficiency is based on the first law of thermodynamics (specific details can be found on the website). To use this calculation method, we need to obtain the inlet/outlet temperature and inlet/outlet pressure values. The inlet temperature and pressure values refer to the air properties at the suction valve of the 1st stage piston. The outlet temperature and pressure values refer to the air properties at the exit valve of the 2nd stage piston. Once we have these pressure and temperature values, we can plug them into our Matlab code and it will output our mechanical efficiencies.
Equipment that are required
- We will be using a J-Type thermocouple from Tempco that is connected to a MAX31856 amplifier board from adafruit and a MSP pressure transducer. These sensors are going to be used to measure the outlet pressure and temperature from the compressor.
Safety Precautions
- Wear safety goggles to protect eyes once compressor is running and wear hearing protection
- Don’t go near the belt area. Wear appropriate clothing (long sleeves, long pants, close toe shoes)
Anticipated time
- This experiment will be roughly 10 minutes. The compressor takes 8 minutes to reach steady state.
Testing Date
- 4/4/22-4/9/22
3. COMPRESSOR EFFICIENCY
Objective
- Calculate the compressor efficiency.
Anticipated results
- We expect the compressor to have an isentropic efficiency between 60-100% based on published values. Depending on how many irreversibilities occur throughout the compression process, the efficiency may drop significantly.
Steps involved for experimentation
- The isentropic efficiency of a compressor is calculated based on the first and second law of thermodynamics, with potential and kinetic energy being negligible.
To use this calculation method, we need to obtain the inlet/outlet temperature and inlet/outlet pressure values from the compressor and tank. The inlet temperature and pressure are of the ambient air. The outlet temperature and pressure values will be determined from the instrumentation. The inlet temperature and pressure values refer to the air properties at the suction valve of the 1st stage piston. The outlet temperature and pressure values refer to the air properties at the exit valve of the 2nd stage piston. One we input these values into Matlab, MATLAB CoolProps will output enthalpy values for each stage, where we can then use the equation
to get the compressor efficiency, where h1 is the enthalpy at the suction valve of the 1st stage piston, h2a is the actual enthalpy at the exit valve of the 2nd stage piston, and h2s is the enthalpy at the exit valve of the 2nd stage piston if the compression process was isentropic.
Equipments that are required
- We will be using a J-Type thermocouple from Tempco that is connected to a MAX31856 amplifier board from adafruit and a MSP pressure transducer. These sensors are going to be used to measure the outlet pressure and temperature from the compressor.
Safety Precautions
- Wear safety goggles to protect eyes once compressor is running and wear hearing protection to protect ears
- Watch hand placement and articles of clothing getting caught in belt (we added the cage surrounding the belt back on to minimize this risk)
- Wear appropriate clothing (long pants, closed toed shoes, hair tied back, no loose jewelry)
Anticipated time
- This experiment will be roughly 10 minutes. The compressor takes 8 minutes to reach steady state.
Testing Date
- 4/4/22-4/9/22
4. PRESSURE OUTPUT
Objective
- Calculate the pressure output from the compressor tank.
Anticipated results
- We are expecting the pressure output to be stable at 100 PSI until the internal tank pressure, which starts at 175 PSI, gets below 100 PSI. From there, the pressure will drop until it has reached a point that it is incapable of running the air motor.
Steps involved for experimentation
- The experiment begins by making sure that the drain valve on the bottom of the tank is closed and nothing is obstructing the belt connecting the electric motor to the air compressor. From here, the compressor is run until it reaches an internal tank pressure of 175 PSI. Then the power to the compressor is turned off so that it will not turn on again. The pressure on the regulator is next set to 100 PSI and the needle valve is then opened to allow air to flow. Finally, an air hose with a quick disconnect valve is attached to the outlet of the compressor to release the pressure. Equipment that are required
- The equipment required to take measurements of pressure is a MSP pressure transducer and a Ardunio mega to read the data. There are also manual pressure gauges as a backup.
- Air hose with ¼” quick air disconnect and air nozzle.
Safety Precautions
- Wear safety goggles to protect eyes once compressor is running and wear hearing protection to protect ears
- Watch hand placement and articles of clothing getting caught in belt (we added the cage surrounding the belt back on to minimize this risk)
- Wear appropriate clothing (long pants, closed toed shoes, hair tied back, no loose jewelry)
- Don’t blow air directly at someone.
Anticipated time
- It is anticipated that it will take around 20 minutes to fully charge and discharge the system.
Testing Date
- 4/4/22-4/9/22
5. COMPRESSOR AMPERAGE/VOLTAGE AND POWER
Objective
- To test the amperage/voltage that the compressor is drawing in so that we can determine the overall efficiency of the system, since overall efficiency is power input divided by power output.
Anticipated results
- The compressor that we purchased can run at 120 V or 240 V and 15 A based on the data provided from the manufacturer.
Steps involved for experimentation
- We will run the compressor in its charging state and measure the amperage and voltage using a meter that plugs into the wall outlet (and the compressor is plugged into the meter). We can then use the equation P = IV to calculate the power input.
Equipments that are required
- Clamp meter
- Electrical outlet to run the compressor
Anticipated time
- This experiment will be roughly 5 minutes.
Safety Precautions
- Wear safety goggles to protect eyes once compressor is running and wear hearing protection to protect ears
- Watch hand placement and articles of clothing getting caught in belt (we added the cage surrounding the belt back on to minimize this risk)
- Wear appropriate clothing (long pants, closed toed shoes, hair tied back, no loose jewelry)
- Check that the meter and other accessories do not have signs of physical damage before using.
Testing Date
- 4/4/22-4/9/22
HEAT EXCHANGER
1. EFFECTIVENESS
Objective
- Calculate effectiveness of the heat exchanger(s)
Anticipated results
- We expect the heat exchanger to have an effectiveness of 7-30%. The low percentages are due to excess losses in the tubes and fittings, and air gaps between tube contacts that limits heat transfer. To obtain higher effectiveness values, more conductive thermal paste or soldering would be considered.
Steps involved for experimentation
- Run the system and take temperature/pressure data. Input system data into our effectiveness calculations MATLAB code. The calculations use Re and Nu correlations to obtain the effectiveness-NTU correlation.
Safety Precautions
- Wear safety goggles to protect your eyes at all times
- Watch hand placement and articles of clothing getting caught in rotating parts
- Wear appropriate clothing (long pants, closed-toed shoes, hair tied back, no loose jewelry)
- Check that the meter and other accessories do not have signs of physical damage before using
- Be cautious of hot pipes
Equipment that is required
- Gauges and thermocouples
Anticipated time
- This experiment will take approximately 15 min to complete as the compressor reaches steady state in ~8min.
Testing Date
- 4/4/22-4/9/22
2. MAXIMUM OUTLET TEMPERATURE
Objective
- Record outlet temperature of outlet air through heat exchanger and into the air motor
Anticipated results
- A maximum outlet temperature that is as close to the compressor inlet temperature is desired. We expect the actual outlet temperature to be lower due to heat transfer losses through the tubing or storage vessel.
Steps involved for experimentation
- Record outlet temperature using thermocouples during the system discharging stage after compressor reaches steady state after ~8 minutes.
Safety Precautions
- Wear safety goggles to protect eyes at all times
- Watch hand placement and articles of clothing getting caught in rotating parts
- Wear appropriate clothing (long pants, closed toed shoes, hair tied back, no loose jewelry)
- Check that the meter and other accessories do not have signs of physical damage before using
- Be cautious of hot pipes
Equipment that is required
- Thermocouples
Anticipated time
- This experiment will take approximately 15min to complete as the compressor reaches steady state in ~8min.
Testing Date
- 4/4/22-4/9/22
TURBINE/GENERATOR
1. EXPANSION SYSTEM NOISE
Objective
- To determine the noise levels created by the high-speed rotating shafts of our air motor and generator as well as system vibrations during the expansion stage and make sure they do not exceed OSHA noise guidelines.
Anticipated Results
- Since the shafts of the expansion subsystem will be rotating anywhere between 300 and 3000 RPM, this will be the most significant contribution to the total noise created by the system. Based on the technical specifications of our air motor, we anticipate noise levels between 80 and 82 dB.
Steps involved for experimentation
- With the compressor turned off, use a decibel reading app at a distance of five feet from the expansion system. Conduct the test in a large, quiet room, such as Leopardworks, to avoid the measurement of noise from external sources.
Equipment Required
- Smartphone with installed noise measuring app
- In-ear or over-ear noise protection
Safety Precautions
- During the operation of the expansion system, wear safety goggles to protect eyes and wear hearing protection to protect ears. This test will determine whether hearing protection will be necessary for future use.
Anticipated Time
- 5 minutes
Testing Date
- 4/4/22-4/9/22
2. POWER OUTPUT
Objective
- Measure the power output from the generator after the entire compression, heat exchanger, and expansion process. We want to measure the optimal pressure input for maximizing the power output.
Anticipated Results
- We expect to power around 500 Watts of lightbulbs at the maximum power output. This power output won’t be maintained as the compressor empties.
Steps involved for experimentation
- We will be using a table top multimeter to measure the current output and will display the power output using a set of incandescent light bulbs in parallel.
- We can also continue adding light bulbs in parallel until the bulbs stop lighting and then we will know we reached the maximum power output.
Equipment Required
- Digital multimeter, electrical wiring, lightbulbs, compressor
Anticipated Time
- This experiment will probably take two lab sessions since we need to fill the compressor and test the output power at different conditions.
Safety Precautions
- Need to make sure we cover the electrical wires so as to avoid any shocks. The maximum voltage is 12-24 volts which is within safe range for humans but we will still be minimizing risk.
Testing Date
- 4/25/22-4/29/29
3. EXPANSION SYSTEM POWER INPUT
Objective
- Measure, plot, and determine the most efficient operating pressure to maximize power output and demonstration time.
Anticipated Results
- We expect efficiency to increase with input pressure. Meaning, the most efficient operating pressure is the maximum pressure achievable by the compressor. However, if we consider demonstration time, a lower pressure is more effective.
Steps involved for experimentation
- Plot relationship between pressures and flow rates for different RPM
- Use these plots to determine a flow rate given an input pressure. Plot power input vs. input pressure and flow rate.
- Divide power out by power in to get an equation for efficiency across the expansion system.
- Plot efficiency versus input pressure and input pressure versus demonstration time to determine most efficient and effective input pressure.
Equipment Required
- Compressor and expansion system.
Anticipated Time
- This experiment will most likely take 2-3 lab sessions because of the number of tests required. The analysis will also take a couple hours.
Safety Precautions
- Need to operate the compressor safely and never raise the pressure to unsafe levels.
- Steer clear of the spinning parts associated with the expansion system.
- Watch out for air exiting the air turbine and any particles carried by it.
Testing Date
- 4/11/22-4/15/22