Structural Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 134

imbalances that they mitigate may be higher). Obviously, the storages may mitigate
only minor imbalances, and this makes it without dif culty; the major imbalances

remain to be mitigated by the control subsystem.
On the other hand, if we look the mCCHP system not as an ensemble of
components (as above), but as a system of links, then we can distinguish two types
of relations, namely physical relations and causal relations.
Physical relation refers to the fact that energy, which is the output of a com-
ponent, is transmitted as input of another component. In this way, there is an energy

flow, which starts from residence energy sources and arrives at the residence

functional needs. Operation follows the energy ow.

Causal relation refers to the fact that one of the two linked components deter-
mines the amount and form of energy transmitted and the other must satisfy this
demand. Thus, there is a causality

flow departing from the residence functional
needs and reaching the residence energy sources. In Fig. 1 the arrows show the
sense of the causality flow. So, the use of

the residence functions determines both the amount and form of energy used by the
consumers, i.e., their consumption. By aggregating consumptions is determined the
power and heat consumptions of the whole system. The storages immediately cover
these consumptions. On the other hand, the

flow. Design process follows the causality

filling level of storages determines the
level of system load so as not to get in trouble. By load sharing is determined how
much each supplier must contribute to fill the storages. This contribution represents
the suppliers load.

1.3 Typical Actions

In the case of a mCCHP system intended for a given residence, the design process
includes the following typical actions:

(1) Problem formulation
In this action, the hypothesis, conclusion, and variables of the problem are
established concretely, so that the latter can be solved during the design process.

Establishing the hypothesis means: (a) estimating the energetic needs of the
residence, (b) identifying the energy sources available in the area where the
residence is located as well as establishing (from the structural and
quantitative point of view) how they may become primary or secondary
energy sources of the mCCHP system.

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Establishing the conclusion of problem means identifying the requirements
regarding the qualitative and quantitative performances, which the system
should meet.

￿

Establishing the variables of problem means: (a) identifying those charac-
teristics of

￿

uence decisively the link between
hypothesis and conclusion, and their consideration as independent variables
of an objective function, as well as (b) identifying those characteristics of the

the system, which in