Testing Prototype 1.0

The first iteration of our prototype is focused on the Thermal Energy Storage (TES) aspect of the product. This follows from our user and technical requirements that we want to create a cookstove that’s able to adequately replace current methods of cooking, which means that it has to be usable at all times of the day and be compatible with the region's electricity infrastructure. Concretely, from a technical standpoint, it has to be capable of operating with off-grid solar and grid infrastructure, and from a user standpoint, it has to operate at least 300 degrees Celsius. As such, our testing plan’s main objective is to determine the efficiency of the thermal energy storage prototype. Below is a testing plan we plan to use for our first major test – testing insulation. We will follow this same structure for future tests. 

Comprehensive Testing Plan

Objective: To determine the efficiency of the Thermal Energy storage prototype in terms of the rate of heat loss and how much it can be minimized, how long 

Materials and Equipment: 

• Cole Parmer Container, 304 SS, 1.25 qt, Internal Vessel
• Cole Parmer Container, 304 SS, 4.5 qt, External Vessel
• ​Fiberglass Insulation Roll
• Induction Burner
• Potassium Nitrate, 10 lb
• Sodium Nitrate, 10 lb

Procedure: Testing Effect of Insulation:

1. Comparing boiling water and its rate of heat loss when placed inside insulated vessel vs regular dissipation (no vessel) 
2. Pour 0.5 kg of water inside internal vessel, then place internal vessel into the insulated TES prototype
3. Place prototype on induction burner then heat vessel until water is 100 degrees celsius
4. Remove prototype from induction burner then test temperature using temperature probe at 15 minute intervals to determine rate of heat loss - this is the test of the insulated vessel
5. When the water has cooled to room temperature, stop recording
6. Repeat steps 1-3
7. Instead of keeping the internal vessel inside the insulation, remove it and place it in open air - this is the test of it with no vessel
8. When the water has cooled to room temperature, stop recording

Variables

• Independent Variable: Insulation or No Insulation
• Dependent Variable: Rate of Heat Output (kW)
• Controlled Variables: Amount of water, Temperature heated to, Size of vessel, Insulation material

Data Analysis

• Place plot points of temperatures to calculate heat output at each interval, then plot a graph of heat output (kJ) vs time (s). Integral of graph will be the power output (kW)

Predicted Results
Q = m x c x t = (0.5 kg) (4.18 kJ/kg x c) (100 - 17.2 degrees C) = 173 kJ heat loss total
Rate: Newton's Law of Cooling: t = -ln[ (T - Tambient) / (Tinitial - Tambient) ] / k 

• Expected time: 42 minutes
• Expected power: 0.068 kW 

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