Category Functional Design of the mCCHP-RES System
The solution of the access in real time by the use of the web in order to process data allows the mCCHP installation to be monitored, unifying in this way the functionality of the remote control with the applicability of the WEB system. The developed application is easy to be configured and easily accessed; it can be visualized and managed to a certain extent in real time by the use of the Internet browser, like any other WEB application, with any type of connection and from any location. The use of the application, the control of the data and of the installation monitoring, allows for data to be stored in a database on a dedicated server, having the ability to connect through an ID and a password.
The software application together with the touch screen terminal from the re...Read More
The experimental data processing and interpretation is possible with SCADA interface. We have 148 variables monitored for experimental data processing and interpretation. The monitoring, control, and protection system through a WEB terminal with real time access from the residential building, equipped with a mCCHP system, is divided in two categories:
a. The monitoring and control system of the residential house
In the monitoring, control, and protection system of the residential house, the monitored parameters are taken directly from the inside of the house with the use of the dedicated equipments and introduced in the database...Read More
One of the basic functions of the automation and control system of the building is a timely control of the procedures and processes that provide an efficient energy operation.
The control programs make sure that the lighting and heating are not automatically shut down at the end of the day, that the building temperature is reduced during the night and that the mCCHP installation does not function more than it is necessary. The operations of switch on time provided by the automation and control system are implemented through the BACnet standard, using the BACnet objects “Schedule” and “Calendar”. This function allows a flexible management of the building. From ordinary programs to unusual exceptions, these functions make the monitoring more flexible...Read More
For simulating the whole system, the scheme presented in Fig. 53 in Chap. “Functional Design of the mCCHP-RES System” was modified considering the equipment characteristics. In this case, the time horizon for the system simulation was 3 days. The sources which discharge in the electric subsystem are the following: Stirling engine, driven by the voltage controller, and PV panel. The power variation graphs of the two sources are shown in Figs. 34 and 35.
Fig. 34 Profile of the power generated by PV panel
Fig. 36 Total consumed electrical power
The electric load has the following components:
• circulation pump of the cold water toward the ventilo-convectors;
• circulation pump of the thermal agent from the pellet boiler to the ho...Read More
For simulation of the whole system, the scheme presented in Fig. 41 in Chap. “Functional Design of the mCCHP-RES System” was modified by taking into account the equipment characteristics mentioned above. The system simulation was done over a 3-days interval.
The operating conditions are given by the following mandatory requirements:
• the thermal power consumed in the domestic water circuit is that given by Fig. 26;
• the consumed electrical power (electrical load) is that shown in Fig. 27...Read More
System operating for mCCHP system is off-grid type. In this case the Stirling engine is in electricity-driven operating mode. The principle applied in the control strategy consists in using the voltage of the electrical energy accumulator and the temperature of the heat accumulation tank, as values sensitive to the misbalance between the produced power and the consumed one. In the case of both accumulations, if the power produced is less than the consumed one, then the electrical/ thermal potential decreases and vice versa. The control system must maintain at constant (nominal) values the capacities through which the electrical/thermal potential (voltage and temperature) are evaluated, by adjusting the produced power.
Thus, the equilibrium between production and consumption...Read More
The DHW circuit is fuelled with energy from the DHW tank. The amount of water is sufficient for the daily consumption of the residence.
This water is heated through conduction from the water of the hot water tank. The continuous refreshing of the water in the DHW tank presupposes resolving the
Fig. 23 Solar thermal panels connecting scheme
problem of calcareous residues with negative effects on the heat transfer. In the case of this tank, the method of the soluble magnesium anode is used.
The thermal load of the circuit is represented by DHW consumption in the adequate spaces (kitchen, baths). The consumption is variable and requires an adequate replacement of the consumed water volume with fresh tap water. The CH10 circuit (Fig. 24) is made up of two parts...Read More
The Stirling engine as cogeneration unit is capable of supplying part of the heat with the hydraulic circuit CH7. The heat transfer from the Stirling engine is achieved through the recirculation of the thermal agent with a recirculation pump located inside the Stirling engine. When selecting care should be taken from the outset to ensure the lowest possible flow temperature (CHP outlet), because the electrical efficiency depends on the cooling water temperature. This should not exceed 65 °C. For this reason the system must automatically vent to the outside the heat. The CH8 circuit has the role of rejecting the heat taken up from the CH7 and
Fig. 22 Stirling heat recuperation and protection hydraulic circuit
of thus maintaining the efficiency of the Stirling engine...Read More