PhD Thesis - Energy Systems Research Unit - University of Strathclyde

simulation tool ESP-r by explaining important principles in ESP-r plant modelling.3.2.1 Modelling a plant network in ESP-rESP-r offers the facility of creating complex plant system models comprising groupsof components linked together in a “network” which can represent a building energysub-system such as a ventilation system or in this case a detailed trigeneration fedHVAC system. This plant network can be integrated with the building model to forma complete representation of the building and its attendant energy systems.In creating plant networks, the first aspect is to select the required componentsthrough an existing database of components library (e.g. ductwork, pipework,cooling coils, heating coils, ventilation fans, pumps, air flow diverters etc.) includedin the tool. Recalling that the main underlying concept of ESP-r is that a complexsystem such as a building or a plant system can be reduced to series of discretecontrol volumes or nodes onto which the basic rules of conservation of energy andmass can be applied [10], a plant network can therefore be considered as a node or aset of nodes (each describing a particular plant component) linked together. For eachcomponent, the user can indicate specific features related to its physicalcharacteristics (e.g. in the case of a duct these would be mass, length etc.) andoperating characteristics (e.g. in the case of a pump these would be the efficiency,rated flow rate etc.). Once all the components have been selected the user thenproceeds to link the different components.In ESP-r plant networks, plant components are connected on the basis of what typeof node is specified. In the ventilation part of a plant network, for example, onlyplant components whose nodes have been specified to represent an air controlvolume can be connected together, such as the case of a duct and ventilation fan.Similarly, for components whose nodes represent a control volume which is liquid(typically water). In the case of plant components with multiple node types, such ascooling coils, heating coils or CHP units each node has to be connected to a plantcomponent having that same type of node. Figure 3.1 shows the case of a coolingcoil. The air flow in this case is sent from the node in Air duct 1 to the node in Air96