Custom Automated Test System – Quantifying Energy and Durability Performance for Refrigeration
Automation reduces manual labor while improving traceability
Assessing performance for improved energy ratings and longevity
Client – Zero Zone – Commercial refrigeration systems manufacturer
Zero Zone wanted to improve the capabilities and durability of their new reach-in refrigeration products.
You might think that refrigeration is a mundane product line, but that is just not true! So many innovations are occurring as manufacturers are redesigning their products to improve their environmental footprint through better energy efficiency, coolants, and durability.
Assessment requires an understanding of the performance of the refrigeration units under many conditions. Zero Zone was taking measurements with a datalogger with too few channels, and no synchronization, to other devices that feed into the system. Plus, they had multiple models of their reach-in refrigerators that needed to be assessed. Furthermore, simplifying the data collection and analysis would make it easier to validate against ASHRAE standards.
Zero Zone came to Viewpoint with the following high-level desires:
- Expand the measurements by adding more channels and channel types (e.g., 4-20 mA, ±10 VDC and digital I/O).
- Provide graphs and KPIs to enable faster analysis of the data during the test.
- Minimize the chance of data loss during long test runs.
- Synchronize data collection and actuation.
- Automate storage of measurements per a user-defined period to eliminate manual start/stop of data collection.
- Simplify the manual configuration setup.
- Enable a way to find relevant data perhaps months or years after the test run.
Viewpoint developed a monitoring and control durability test system that could exercise Zero Zone’s refrigerators through hundreds of operation cycles over multiple conditions to simulate actual usage in, for example, a grocery store.
During initial conversations, we collaborated closely with Zero Zone to brainstorm on some potential approaches. We made some suggestions that could satisfy their desires while also managing their time and cost budgets.
For example, by automatically populating the cells in an Excel template based on their original systems’ Excel spreadsheet, we provided streamlined report generation without having to rewrite all the calculation code embedded in their Excel file in another app. The compromises we jointly endorsed were:
- Run an app on a PC to configure and monitor the test.
- Use both NI Compact RIO and Compact DAQ to enable robust and synchronized data collection and control with the ability to expand channels by adding modules in both the cRIO and cDAQ chassis.
- Store data on a local PC rather than a remote server to minimize the probability of data lost during the test run.
- Save configurations into Excel files for recall, and cloning, of prior setups.
- Write measurements automatically into the same Excel file for archive of the test setup and measurements.
- Create, in this same Excel file through cell formulas, the summary report from the summary calculations. This approach allowed flexibility for changes to internal and external test standards.
- Upload the summary data and test reference info into a SQL database for data management and long-term test statistics.
Digital outputs (DOs) were used to control various aspects of the test, such as door open/close and defrost on/off cycles. For flexibility, the user can specify the sequencing of these DO channels, in the Excel file used for the test, with various parameters that define the duty cycle, period, number of cycles, and start delay. The timing of these DO state changes was synchronized to the data acquisition by the real-time loop in the cRIO.
This system was deployed to 6 test bays, each one of which might be testing a unit for as little as a few weeks or as much as a few months.
The main goal of this project was to reduce the effort and associated human error in the design and execution of the test run.
Some of the primary benefits for this automated system were:
- Reduced Errors: pre-verified template files used for test configuration and data storage lent consistency to test setup and execution.
- Less Testing Time and Effort: the automatic execution of the test and storage of measurements enabled running tests for multiple days (and nights) without technician interaction. Technicians could work on setting up other units for test rather than babysit the existing test. On average, based on the duration of the test time, testing throughput increased by approximately 25% to 40%.
- Shorter Reporting Time and Effort: reports were available about 85% faster than the time previously spent creating manually. The quicker feedback saved costs through early detection of unit problems and faster teardown at the end.
Some additional major benefits were:
- More details on refrigerator operation: “Wow! We never saw that before.”
- Database consolidation: statistical analysis takes hours not days and includes all tests run in the lab, not just ASHRAE tests. This central database enables long term retrieval of all test data.
- Reuse: techs embraced ability to reuse and modify previous setups.
- Consistency: driving the test definition through an Excel file encouraged uniformity.
- Traceability: documented and timestamped calibration measurements.
- Flexibility: channel counts, acquisition modules configuration, calibration, and calculation formulas were straightforward to change for new test setups.
The test automation provided by this system greatly reduced the labor involved in configuring, running, and analyzing the test run. Furthermore, the customer benefited from the consistency that resulted from the software-enforced process.
We developed the application in LabVIEW and LabVIEW RT combined with a cRIO connected to a cDAQ via TSN Ethernet.
The data acquisition modules slotted into the cRIO and cDAQ chassis handled the I/O to the customer sensors and actuators. The sensors mostly measured:
- power, and
|Data logging of between 50 and 150 channels and control via digital signals|
|Interface with Excel files for configuration, data logging, and summary calculations|
|SQL database for summary and test setup data|
|Real-time loop for robust operation|
|NI cRIO 8-slot chassis, TSN enabled|
|NI cDAQ 8-slot chassis, TSN enabled|
|Various NI cSeries signal conditioning modules|