Research Output
1 - 2 of 2
Publication
Co-simulation of a HVAC system-integrated phase change material thermal storage unit
2017, Jones, A. T., Finn, Donal
A co-simulation environment, consisting of a detailed mathematical model of a thermal energy storage unit which is incorporated with an EnergyPlus simulation model of a full building HVAC system, is described. The two models are integrated using the user-defined plant component feature in EnergyPlus and the Building Controls Virtual Test Bed (BCVTB) environment. The thermal energy storage unit, which consists of encapsulated phase change material in a series of flat plates and a heat transfer working fluid (water), is modelled using a transient one-dimensional forward finite difference method. The thermal storage model is executed within MATLAB and is verified against experimental data, showing a discharging heat transfer accuracy to within 2.5%. The building model, which incorporates a retrofitted ground source heat pump system within a thermally massive building, is simulated in the EnergyPlus environment. The co-simulation arrangement allows for in-depth analysis of the integrated system under dynamic operating conditions, which is currently not possible within the EnergyPlus environment. Moreover, the overall adopted approach, based on generic integration of a detailed mathematical model, using a third party generalised programming environment, into an established building simulation environment, serves as a successful exemplar for other researchers and practitioners working in the field.
Publication
Evaluation of a Ground Source Heat Pump System for Varying Loads and Return Water Temperatures using Different System Performance Factors
2011, Edwards, Killian C., Jones, A. T., Finn, Donal
A quasi-steady state mathematical model of a ground source heat pump has been developed. Heating
and cooling is delivered to the building using fan coil units, which are either in constant operation
(Strategy 1) or switched on/off as water flow to the coil is diverted (Strategy 2). The performance of
the system is evaluated using a system performance factor (SPF). It was observed that values for SPF4
(which includes all components) decreases for decreasing building load. For strategy 2, the energy
saving associated with SPF4 are greater than Strategy 1, but savings are diminished at higher loads.
Improved system performance was observed at lower return water temperatures in heating and higher
return temperatures in cooling. However, in both cases the capacity of the fan coil units is reduced.
The temperature compensation strategy developed resulted in an improved SPF4 for Strategy 1 and a
less significant improvement for Strategy 2.