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Test Plan

P8404 – Second Gen. Solar Pasteurizer

Rev C – 3/21/2008

Ben Johns

Adam Yeager

Brian T Moses

Seby Kottackal

Greg Tauer

Faculty Advisor

Dr. Robert Stevens

Rev A – 2/23/2008
Rev B – 3/15/2008
Rev C – 3/21/2008

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Scope

This test plan covers all known testing activities that will need to occur for completion of the P8404 Senior Design project “Second Generation Solar Pasteurizer” at RIT.

Location

All testing will be carried out at Rochester Institute of Technology, located in Rochester, NY. All tests will be performed between March and May, 2008.

Objective

The primary goal of testing will be to verify certain quantitative engineering specifications have been met. A secondary goal will be to benchmark subsystem performance in an effort to identify opportunities for improvement.

The following engineering specifications will require direct validation through testing (starred * will require translation from testing in Rochester, NY to a representative Haitian climate through a model):

Tested By / Spec # / Metric / Ideal Value / Marginal Value
Full Test / 1 / Achieved Safety Zone / Binary
MTF / 2 / Density of Coliform group members / 0 / 5
Full Test / 3 / Output Quantity * / 100 / 25
Setup Test / 7 / Median set up time / 15 / 60
Full Test / 9 / Highest Temp of External Housing * / 60 / 86
Full Test / 13 / Operating Temperature of Pasteurization / 70 / 65
Full Test / 14 / Time to Reach Operating Temperature * / 60 / 120
Leak Test / 16 / No Unpasteurized Water Output / Binary
MTF / 17 / Kill Rate of Harmful Pathogens / 99 / 100

Table 1: Specifications requiring validation through testing

Additional testing will be performed on a selection of the pasteurizer’s subsystems in an effort to benchmark performance and validate the conceptual models required for climate equivalency conversion. These subsystem tests will also be used to help drive iterative improvement in these vital areas.

For detailed descriptions of the tests to be performed, see “Tests” section below.

Model

Since testing will be performed in Rochester, NY but the engineering specifications are set for a Haitian climate, a method for translating from results in Rochester to expected results in Haiti will be required.

A model will be developed to predict the quantity of expected water pasteurized over the course of a day as a function of

  • Ambient air temperature,
  • Solar Irradiance, and
  • Input water temperature.

The parameters to the model (referred to further as the “model inputs”) will be a collection of hourly averages over the course of the day under analysis.

During testing, the model will likely need to be modified as inaccuracies are found. All changes to the model resulting from empirical testing will need reasonable theoretic backing to strengthen the model’s ability to forecast outside the test range.

After testing, the model’s ability to accurately predict the resulting pasteurized water output will be assessed. The model will be assumed valid for use if, over three good but slightly different days, the model does not under predict final water output by more than 10%.

As required, other statistical methods will be employed to further explain model variability and increase the model’s power and accuracy.

After this model’s accuracy has been demonstrated to be reasonable, specifications for Haiti will be evaluated. Each day of test data in Rochester will be modified to represent, as closely as possible, the climate of Haiti. Specifically, the model inputs collected from testing in Rochester will be scaled by appropriate factors, as determined from a comparison of hourly weather data, to represent a Haitian winter day and a Haitian summer day.

Results of the analysis of this model for the representative winter days will demonstrate the expected low range of the engineering specifications as the summer days will demonstrate the expected high range.

Test Equipment

Labview

A PC with an installed copy of Labview and the required sensor interfaces will be required for the full test of the pasteurizer. A VI program will be written to read the value of sensors every (1) second, log these values, and provide an adequate level processing for real time feedback on the state of the system. The logged data will later be combined into a collection of 10-second averages.

Thermocouples

Thermocouples will be used to measure temperature at various parts in the system. All thermocouples that will be used are categorized as type T, which are good for measuring -185 to +300 C continuous, with -250 to +400 C short term measurements. Two types of thermocouple packaging will be used. One type is designed to be attached to a flat surface through an integrated silicone based adhesive backing. These thermocouples will be used to measure the temperature of plates and glazing. The second type of thermocouple package used will be probe type. These thermocouples will be used to measure water temperature and will be attached to the system using funeral plumbing fittings.

Pressure Sensor

An integrated silicone pressure sensor with on-chip signal conditioning and temperature compensation will be used to measure pressure. The specific model that will be used is Freescale Semiconductor model number MPX5010DP, capable of sensing a maximum pressure difference of 1.5 PSI.

Pyranometer

A LI-COR 200SZ pyranometer will be used to measure solar irradiance during testing.

Test Setup

All tests will require a complete prototype with the necessary sensors attached. The following sensors will need to be interfaced to the system at the functional points described by the following schematic.

Figure 1: Schematic view of pasteurizer operation with sensor locations called out.

Figure 2: Detailed view of proposed valve design with thermocouple sensing locations indicated. Detailed design of thermocouple interface will be completed in next valve design iteration.

Flat Adhesive Thermocouples (A, B, C)

  1. This thermocouple will measure the outside temperature of the glazing to verify spec 1.
  2. This thermocouple will be placed on the expected hottest surface of the collector plate. This sensor will be used to benchmark the performance of the collector subsystem.
  3. This thermocouple will be placed on the expected coldest surface of the collector plate. This sensor will be used to benchmark collector subsystem performance.

Probe Type Thermocouples (1, 2, 3, 4, 5)

  1. This thermocouple will measure the water temperature in the valve on its hot side. The temperature read by this thermocouple can be used to determine if the valve should be open or closed.
  2. This thermocouple will measure water temperature on the cold side in the valve. If the valve is open, this thermocouple will read the temperature of the valve output water, which must be greater than 70 C per spec 13.
  3. This thermocouple will be used to measure water temperature at the exit to the hot water reservoir immediately before it enters the hot side of the heat exchanger. This thermocouple is needed to verify specifications 13 and 1.
  4. This thermocouple will measure water temperature at the cold water inlet to the heat exchanger to use as an input to the equivalency model.
  5. Changes in ambient air temperature will be measured by this thermocouple.

Pressure Sensor (a)

  1. Relative pressure will be sensed between the bottom of the output bucket against the ambient air pressure. This sensor will allow for computations of flow rate to be made and is required to help verify specifications 1, 3 and13.

Pyranometer

A pyranometer will be used to measure solar irradiance. This will be required to validate for accurate modeling of the pasteurizer’s behavior.

Tests

Test 1: Setup Time Test

To specification 7, “median setup time from shipping state”, a setup test will be performed using a sample of human subjects. These subjects will be given pictorial instructions on how to setup the device, and then timed.

An initial pilot study involving 5 subjects will be carried out. More samples will be collected, depending on experimental variance, to assure this specification is met at an alpha level of .10.

Test 2: Leak Check Test

To assure the thermostat valve does not leak, as required for specification 16, a leak check will be performed. This test will also test the quality of system plumbing, an important consideration to unit efficiency.

The pasteurizer unit will be filled with water, then set in shade and monitored periodically for 24 hours. Any leaks will be documented. Should the valve leak, the resulting volume of water in the output bucket will be measured.

This leak check test will be performed last, or after the unit is in its final configuration.

Test 3: Full Test

Ultimately, a full test of the unit will be required to prove if it behaves as expected. This test will be performed on every day permitted by weather conditions, until enough samples have been collected to:

  • Determine if the target specifications have been met and
  • Validate the model used to describe these parameters as required for climate equivalency translation.

The majority of the target engineering specifications will be measured by this test.

Specification “1 - Achieved Safety Zone” and “9 - Temperature of Pasteurization” will be measured by thermocouples “2” (before hot water reservoir) and “3” (after hot water reservoir), in conjunction with the flow rate as determined by pressure sensor “a” (pressure at bottom of the output bucket). The unit must be operating in the safety zone while there is a flow rate.

Specification “3 - Quantity of Output” will be validated by measuring the quantity of water in the output bucket at the end of testing.

Specification “9 - Hottest External Temp” will be examined by identifying the highest reading of sensor A, the thermocouple on the outside of the glass pane near the top 1/8th of the glass collector cover.

Specification “14 – Time to Operating Temperature” will be measured by thermocouples 1 and 2, the water temperature sensors on both sides of the valve. Time to operating temperature will be defined as time from which enough solar irradiance exists to pasteurize water to the time the unit actually outputs pasteurized water.

Test 4: Multiple Tube Fermentation (MTF)

This test will be carried out with assistance from the Biological Sciences Department at RIT. After the full operational test is performed, a sample of the used input and resulting output water will be tested for the presence of Coliform organisms.

Input water will be collected at a location likely to yield a high Coliform density. The sample of this input water used for this test will be collected and preserved before testing is performed. The first 2 liters of output water will be ignored. The final output sample used will be collected from the output bucket, shortly after being stirred, and after all pasteurization has stopped for the day. Should more than one bucket of water be output, a sample will be tested from each.

The resulting absolute value of most probable Coliforms per 100 ml of the output water will evaluate specification “2 - Resulting Coliform Density”, and the ratio of the input to output concentrations will assess specification “17 - Kill Rate”.

To aid in comparison, water with similar levels of contamination will be used across days of testing.