In the past, controlling the indoor climate in homes consisted of a thermostat regulating the heat, and ventilating the homes by opening the windows. New energy performance regulations have led to more insulated and airtight houses, as well as increased energy performance requirements of indoor climate systems.
Maintaining a comfortable indoor cli- mate in a modern house now also involves control of fresh air, protection against overheating, and passive cooling. New homes have multiple systems to handle these tasks: mechanical ventilation systems with heat recovery, heat pumps, radiator or floor heating systems, solar shading systems, and systems for passive cooling. Each of these may work efficiently under ideal conditions, but often these systems have an impact on each other, leading to discomfort and higher energy consumption than expected.
Danish company Danfoss A/S (Gråsten, Denmark), a maker of energy and climate solutions, decided to build the world’s first test center to test indoor climate systems. The test center is capable of controlling and monitoring both energy generators (heat pumps, gas boilers) and heat emitters (radiators, floor heating), as well as controlling the simulated outdoor environment in a climate room. The heart of the test center is a unique control and data acquisition system developed by CIM Industrial Systems A/S (Struer, Denmark) in cooperation with Trimatic Automation A/S.
The test center, which was completed in 2013, consists of three separate test cells constructed with different materials in the walls and floors. The test cells are surrounded by a climate room that simulates outdoor temperatures from -20 °C to +30 °C, regardless of the weather outside.
Danfoss chose CIM for the assignment because of its control and measurement expertise; Trimatic designed and manufactured the control panels and boards in the test center. For CIM, the challenge was creating a completely customized hard- ware and software solution that was scalable, efficient, and available 24 hours a day, seven days a week.
Using hardware and software from National Instruments (Austin, TX), CIM created a control and measurement system that allows engineers at Danfoss to execute tests in parallel in the three test cells. The engineers can easily set the variety of test conditions in test profiles and save them in the system. This makes it easy for engineers to repeat tests with exactly the same conditions and compare the results.
The backbone of the system is the NI CompactDAQ hardware with Ethernet connectivity. The hardware was integrated with LabVIEW software using NI-DAQmx driver software, which enabled scaling and signal conditioning close to the hardware level. The CompactRIO platform was chosen to control the KV Stand because it can help to create and deploy time-critical and advanced control algorithms using the LabVIEW Real-Time and LabVIEW FPGA modules.
On the software level, a new object-oriented data logger framework was developed in LabVIEW. The new framework created a solid foundation for the solution, and based on that, CIM constructed a scalable, stable measurement platform that supports a high level of flexibility for new devices.
The system is controlled by a client program and a server program. The client controls the graphical user interface and starts and stops test profiles; the server controls all the modules that interface with the control and measurement equipment in the test cells. From the client PC, engineers can monitor all sensor data from the test cells, including air temperature, operative temperature, and relative humidity. All data are automatically logged to a Microsoft SQL database to ensure traceability. Engineers also can configure test setups and test profiles, and retrieve data from the database from any PC through a Web application.
Danfoss can now test products more rigorously and much faster than before, which boosts overall quality and reduces time to market for its energy and climate components.
This article was written by Morten Pedersen of CIM Industrial Systems and Klaus Lund Nielsen of Danfoss, using hardware and software from National Instruments. For more information on National Instruments products, visit http://info.hotims.com/55586-420 .