NaturaFill © 2013, TEAM 13, CALVIN COLLEGE Last Updated: 4/1/2014

PROJECT BRIEF NaturaFill: Fuel for Thought

Team 13 Karl Bratt Jonathan Haines Brandon Koster

Project Brief Last Updated: 4/1/2014

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1 Project Overview

1.1 Problem Statement There is scarcity in the residential applications for compressed natural gas (CNG) in the United States

transportation landscape. Currently, only 605 public CNG refueling stations exist, compared to the

168,000 gasoline stations.1 In response, a few small companies, such as BRC Fuelmaker, have

developed home refueling units that run on electricity and connect to existing natural gas lines.2

Unfortunately, these models begin at $5,000 before installation.3

1.2 Project Objective The objective of NaturaFill is to design, build, and test a natural gas home refueling appliance that is

lower cost and more reliable than the appliances currently on the market.

1.3 Design Requirements

1.4 Team Organization:

Karl Bratt 1.4.1.1

Bratt is a Mechanical concentration engineering student also in pursuit of a business

minor. Bratt is primarily responsible for the organizational components of the

project. This includes, but is not limited to, the planning and scheduling of team

meetings, review and on-time delivery of project deliverables, and work breakdown

of tasks among the team member using Microsoft Project.

Jonathan Haines 1.4.1.2

Haines is a Mechanical concentration engineering student also in pursuit of a

mathematics minor. Haines’s experience with thermodynamics and manufacturing,

along with his knowledge of Autodesk CFD simulator, has been valuable in the design

and testing of the system. In addition, Haines has used his experience in

manufacturing to machine the system’s metal components and parts

Brandon Koster 1.4.1.3

Koster is a Mechanical concentration engineering student also in pursuit of a

business minor. Koster has significant background knowledge in the industry, which

has served to connect the team with companies and individuals able to provide

guidance and support throughout the project. In addition, his experience with

compression systems has helped in performing design calculations, ordering parts,

and forecasting the overall cost of the system.

1 http://www.afdc.energy.gov/fuels/natural_gas_locations.html

2 http://www.cngnow.com/vehicles/refueling/Pages/refueling-at-home.aspx

3 Jimmy Moerdyk, Moerdyk Energy Inc. (MEI), 9/27/13, 9:00AM

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2 Design Decisions

2.1 Hydraulic System A hydraulic system will be used to convert electrical energy into mechanical work that will drive the

pistons a therefore compress the gas. An overview of the proposed hydraulic system is shown below

in Figure 1: Hydraulic System Schematic. The images describe current

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2.2 Natural Gas System

Small Parker Hydraulic Cylinder

(testing only). Full-scale

cylinder still to be purchased.

Ashcroft 5000 psi

Pressure Gauge(s)

D03 Solenoid-Operated

Hydraulic Control Valve

5000 psi Tubing w/ 3/8”

SAE Straight Thread Fittings

1.25 Gallon Hydraulic Pump & Reservoir

Monarch Hydraulics Inc.

Figure 1: Hydraulic System Schematic

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The natural gas system will move the gas from a residential natural gas line, through each of the two

compression cylinders, and ultimately into the tank of a natural gas vehicle. It also is designed to

prevent backflow at every possible point and monitor the thermodynamic state of the natural gas

using thermocouples, pressure gages, and a pressure transducer. A schematic of the natural gas

system is shown below in Figure 2: Natural Gas System Schematic.

2.3 Sealing System

2.3.1 PTFE Coated Cylinder Walls PTFE (Teflon) coated cylinder walls will provide an excellent low-friction surface for the piston rings to

move along. This coating will protect against provide an excellent low-friction seal and protection

against excessive wear on both the cylinder wall surface and the rings. This coating is most common

in oil-less compressor designs.

2.3.2 PTFE Seal Rings Two PTFE (Teflon) seal will be used to seal the gas

inside the compression chamber. These rings

provide an excellent, low fiction seal. These rings

will be located to the inside of the two rider rings,

as displayed below in Figure 37.

2.3.3 PTFE Rider Rings Two PTFE (Teflon) rings will be used to stabilize

the piston as it moves up and down the cylinder

walls. These rings will be located to the outside of

the two seal rings, as displayed below in Figure

37. Figure 2. Sealing System Schematic

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Figure 3: Control System

2.4 Control System The controls for the system will be managed by

National Instruments: LabVIEW 8.5. Using

National Instruments input, output, thermocouple,

power supply, and Ethernet modules, the team

will monitor the temperatures and pressures at

each stage in the system and program emergency

stops if either exceed safe operating conditions

(see Figure 4: Control System). Work is currently

underway to have the control system programmed

and operating by mid-March.

3 Significant Issues

3.1 Loss of an Electrical Engineer At the beginning of February 2014, our team was notified that our fourth member, the only electrical

engineer in the group, was dropping out of engineering. This was shocking news. Discussions arose

over which of us three mechanical engineers would take his place. Having purchased a Raspberry Pi

development board, the team began researching how to program it. We realized this was beyond our

technical knowledge and began looking into other control module alternatives.

3.2 Lead Time on Seals Finding appropriate seals for the compression cylinders has been a challenge. Recognizing that they

must withstand high pressures and temperatures, there are few suitable models available. After

reaching out to Zatkoff Seals & Packaging in Grand Rapids, the team eventually found a Parker seal

that that would satisfy the system’s requirements. Unfortunately, on February 26, the team was

informed of a 6-8 week lead-time on such seals. This development has modified the team’s original

plan of constructing a fully-functional preliminary prototype before the final. In addition, it moved up

the final design decision deadline so that the final prototype seals may be ordered in the next few

days.

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Figure 4: CFD Pressure Distribution

Figure 6: Preliminary Prototype CAD Model

4 Current Status

4.1 Modeling In order to determine the size requirements for the

natural gas compression cylinders along with the tubing

connecting the cylinders, the team has used a

combination of Engineering Equation Solver (EES) and

Autodesk CFD simulator, as shown in Figure 5. These

have enabled the team to monitor the pressure and

temperature distribution throughout the compression

cylinders.

In addition, the team has modeled the preliminary

prototype in Autodesk Inventor and Algor to understand

the system’s stress distribution during operation (See

Figure 6). The final has been shown in the Appendix.

4.2 Prototype Construction of the final prototype is underway.

Currently, the team has obtained 140 pounds of plate

steel, of which the manifolds are being machined out of.

In addition, the team plans to have the hydraulic system working with a test hydraulic cylinder by

March 10.

4.3 Controls As shown in Figure 4, the team is currently programming a VI in LabVIEW 8.5 with the appropriate

input and output controls necessary for the final prototype. Once the pressure transducers arrive, the

team will be able to begin testing the VI for functionality.

4.4 Budget

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4.5 Appendix

Figure 5: Final Design Model