Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 228

7.4 Performance Evaluation of the Potential Structural
Models

7.4.1 Evaluation at the System Level

In the fourth step of the design process have been identi ed the potential structural

models by customizing the general structural model. Table 7 shows the set of
identi

ed potential structural models. Now the performance of these models should
be evaluated in order to retain the best. The structural models can be obtained from
the particularization of the cooling system (with mechanical compression or with
thermal compression) and of the auxiliary sources (with thermo solar panels or with
photovoltaic panels). With all the structural models, the electric load control is
achieved by adjusting the fuel consumption of the Stirling engine, and the thermal
load control by controlling the fuel consumption of the additional boiler. The next

set of potential structural models refers to the off-grid case only. In what follows,
the retained models are presented in more detail.
Model 1. In this structural model, the electrical energy is produced by two
sources: the Stirling engine and the photovoltaic source (PV panel). Both sources
recharge the battery. The thermal energy is produced by three sources: Stirling
engine, a boiler and a ST panel, all being collected into an accumulation tank. The
thermal energy accumulated in the tank is used for domestic water heating and for
the residence heating in winter regime. It is also used for air conditioning and
domestic water heating in summer regime (thermal compression chiller). The
structure of the conditioning equipment contains an accumulation tank for the cold
agent.
Model 2. The electrical energy is produced by a single source

—

the Stirling
engine. The thermal energy is produced by three sources, as well as in model 1,
namely Stirling engine, boiler and ST panel.
Model 3. The difference as compared to the previous model consists in the fact
that, the ST panel is missing.
Model 4. In this structural model, the electrical energy is produced by the Stirling
engine and by a PV panel. The thermal energy is produced only by two sources:
Stirling engine and boiler.
Model 5. The case in which the air conditioning uses electrical equipment is
considered. In this structural model, the electrical energy is produced by the Stirling
engine and a PV panel, while the thermal energy is produced only by two sources:
Stirling engine and the boiler.
Model 6. The case in which the air conditioning uses electrical equipment is
considered. In this structural model, the electrical energy is produced by the Stirling
engine and a PV panel, while the thermal energy is produced by three sources:
Stirling engine, boiler, and ST panel.
Performance indicators of the described models are presented in Fig. 47
Therefore, we note that the best models are that which use both the PV and ST
panels. At

—

the same structure of energy sources, the model with thermal