Progress Report 1

Over the period of October 30 – November 7, we continued our work on the delivery system of our prototype for the autonomous firefighting device. Initially, we had planned to use a solenoid piston to compress a cylindrical compressor container that would then blow a fire extinguishing powder out, however, the force exerted by the piston was not enough to compress the container. We found that a much larger and quicker force would be needed to compress the cylindrical container to blow the powder out, however, a piston with that power was difficult and expensive to acquire. Instead, we decided to use an air blower that will be connected to a network of plastic tubing along with a nozzle to blow the powder out at the target fire. As our extinguishing powder is of a very low density, we decided to use a 16 CFM (cubic feet per minute) air blower as it can provide enough force to easily blow the powder out through the nozzle. The following figure demonstrates our design idea for the delivery system of the device. 

Figure 1: Rough Sketch of Powder Delivery System

The powder will be dropped into a plastic tube by multiple outlets after the infrared flame sensors and LDR have sensed a fire. The air blower will also turn on and blow the powder towards the nozzle and out towards the target fire. If the sensors sense a fire, more powder will be dropped down and the cycle will repeat itself. When looked closer at this cycle, however, we ran into a problem. The electrical components of the device will be controlled through Arduino except for the air blower. Turning the air blower on and off through code seemed to be impossible due to it being connected directly to a 12V adapter power supply. Through research, it was found that a relay switch model could allow for the control of the blower. The relay switch will be connected to the Arduino board and to an external power supply along with the wiring of the air blower. This module will be coded to cut power to the air blower after a fixed amount of time and then start again if needed.

A rough prototype to test this delivery system was constructed. As seen in the pictures below, the air blower is connected to a plastic tube through sealed adapters. Initially, our prototype would use a straight line of tubing. However, because of the device’s dimensional constraints being 10 x 10 x 6 inches, it was decided that an elbow would be used to make a 90-degree turn for the plastic tube to allow for more room for the powder to drop down into the pipes.

Figure 2: Initial Powder Delivery system

Figure 3: Modified Powder Delivery System with Elbow

Several tests were conducted to see if the air blower blew out the powder with enough force when using an elbow. As seen in the video below, the fire extinguishing powder was loaded into the plastic tubing by a funnel and the top inlets were sealed. The air blower was then connected to the power supply. The blower effectively blows the powder out through the ending of the plastic tube. Various amounts of the powder were loaded into the tubes to see if the blower would still blow the powder out and it was effective every time. We are satisfied with the results of this air blower delivery system and are working on ways to make it even more effective and efficient.

Figure 4: Powder Delivery System Video

From November 7 to November 21, we plan to work on conducting our FEA on COMSOL and conducting computational fluid dynamic analysis for our design through ANSYS. We will also work on the 3D models of our design on SolidWorks to finalize the design. These designs will be utilized to test for stress and heat resistance. As our team has very limited knowledge of how to use ANSYS, we will be watching various tutorials and preparing ourselves on how to conduct the CFD on the airflow of the powder delivery system. 

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