Category Functional Design of the mCCHP-RES System

The mCCHP-SE-RES System Data

Nicolae Badea

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...

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System Interface

Nicolae Badea

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...

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Design of the Control Subsystem

Nicolae Badea and Marian Barbu

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...

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System Dynamics Analysis in Summer Regime

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:

• hydraulic station pumps for the adsorption chiller;

• circulation pump of the cold water toward the ventilo-convectors;

• circulation pump of the thermal agent from the pellet boiler to the ho...

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System Dynamics Analysis

Marian Barbu

5.2System, Dynamics Analysis in Winter Regime

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...

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System Operating and Control

Nicolae Badea

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...

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Circuit of DHW (CH10)

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...

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Circuits of the cogeneration unit devoted for heat recuperation and protection (CH7 and CH8)

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...

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