Functional Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 282

thermal balances in steady-state regime. In this case, the temperature values
within the residence, according to the requirements of the thermal comfort and
the extreme values of the external temperature, in winter and summer regimes,
are imposed. The balances determine the powers necessary to ensure the
temperature values imposed in the residence. They are achieved by two cal-
culus program which, in what follows, will be called winter thermal balance
(WTB) and summer thermal balance (STB), respectively.
(c) The electrical load of the system is made up of two components:

the useful electrical load of the residence, generated by the consumers
within the residence (illumination, refrigeration etc.);

￿

the load generated by the equipment ' s own consumption (the consumption

￿

of pumps, ventilators etc.).

The useful electric load is adopted as a diagram of the power consumed in 24 h,
which must be as close as possible to the average diurnal consumption. Figure 22
presents the diagram of the diurnal useful power. It is the same for both winter and
summer regimes. The electrical load determined by the equipments own con-
sumption is a variable value, whose time evolution depends on the controls given to
various equipments of the system.
(d) The thermal load of the system is also made up of two components:

- a slow variation component necessary to bring the residence temperature to

the desired values. This component modi es on the temporal scale of

the weather conditions evolution and it will be considered constant in the
numerical simulation. In simulation, the component of the thermal load is
supplied by the calculus programs, WTB and STB;

- a fast variation component representing the power consumed in the

domestic water circuits (kitchen and bathroom). The graph of variation in
24 h for this component is adopted so that it should be close to the diurnal

Fig. 22 Graph of the useful
electric power consumed in
24 h

Electrical power consumption / 24 hours

4.5

4

3.5

3

2.5

2

1.5

1

0.5

0

0 1 2 3 4 5 6 7 8

x 10 4

Time [s]