Six-Day System Test and Component test and System Simulation for Combitanks with Internal heat Exchangers

An international standard, ISO/DP 9459-4 has been proposed to establish a uniform standard of quality for small, factory-made solar heating systerns. In this proposal, system components are tested separatelyand total system performance is calculated using system simulations based on component model parameter values validated using the results from the component tests. Another approach is to test the whole system in operation under representative conditions, where the results can be used as a measure of the general system performance. The advantage of system testing of this form is that it is not dependent on simulations and the possible inaccuracies of the models. Its disadvantage is that it is restricted to the boundary conditions for the test. Component testing and system simulation is flexible, but requires an accurate and reliable simulation model.The heat store is a key component conceming system performance. Thus, this work focuses on the storage system consisting store, electrical auxiliary heater, heat exchangers and tempering valve. Four different storage system configurations with a volume of 750 litre were tested in an indoor system test using a six -day test sequence. A store component test and system simulation was carried out on one of the four configurations, applying the proposed standard for stores, ISO/DP 9459-4A. Three newly developed test sequences for intemalload side heat exchangers, not in the proposed ISO standard, were also carried out. The MULTIPORT store model was used for this work. This paper discusses the results of the indoor system test, the store component test, the validation of the store model parameter values and the system simulations.

Opening discourses of citizenship education : a theorization with Foucault

We argue two major difficulties in current discourses of citizenship education. The first is a relative masking of student discourses of citizenship by positioning students as lacking citizenship and as outside the community that acts. The second is in failing to understand the discursive and material support for citizenship activity. We, thus, argue that it is not a lack of citizenship that education research might address, but identification and exploration of the different forms of citizenship that students already engage in. We offer a fragmentary, poststructuralist theorization oriented to explore the contemporary limits of the necessary', drawing on specific resources from the work of Michel Foucault and others for the constitution of local, partial accounts of citizenship discourses and activities, and exploration of their possibilities and constraints. We argue this as a significant tactic of theorization in support of an opening of discourses of citizenship and in avoiding the discursive difficulties that we have identified. Our theorization, then, is significant in its potential to unsettle discourses that confine contemporary thought regarding citizenship education and support exploration of what might be excessive to that confinement.