Some comments about the use of GHP in Alentejo (Portugal)

In this work we advocate the use of geothermal pumps to cool the isolated houses that can be observed in the plain of Alentejo. Passive cooling of the houses, made for centuries, becomes insufficient when it aims to promote tourism in the region. The climatic characteristics of the region and the relatively high values of the thermal conductivity of the ground favour this type of use. The available land around the houses provide places where you can drill or make trenches to put the pipes under the surface . Some values of pipe lengths were obtained using values appropriate for the region. The need to try to preserve the shape of the typical houses of the region discourages the use of solar panels placed on the roofs. The length and time of use of the equipment is another factor to take into account in the analysis of the costs.

Application of Mixture Models to Survival Data

Survival models are being widely applied to the engineering field to model time-to-event data once censored data is here a common issue. Using parametric models or not, for the case of heterogeneous data, they may not always represent a good fit. The present study relays on critical pumps survival data where traditional parametric regression might be improved in order to obtain better approaches. Considering censored data and using an empiric method to split the data into two subgroups to give the possibility to fit separated models to our censored data, we’ve mixture two distinct distributions according a mixture-models approach. We have concluded that it is a good method to fit data that does not fit to a usual parametric distribution and achieve reliable parameters. A constant cumulative hazard rate policy was used as well to check optimum inspection times using the obtained model from the mixture-model, which could be a plus when comparing with the actual maintenance policies to check whether changes should be introduced or not.

Abstraction and use of groundwater for heating buildings in a hard rock environment

In order to turn more efficient the heating of class rooms in the lower floor of the old building of the University of Évora (a XVI century building), five drillings were organised inside the area of the university (Figure 1). The purpose was to use the temperature differential of groundwater in relation to air, by means of a heat exchanger, and use this process to heat the rooms using less energy, turning the heating process less expensive. The wells were drilled in fractured rocks (gneisses), and the purpose was to locate them at least around 100 m one from each other, whilst trying to have a hydraulic connection in-between. From the five initial wells, four were successful in terms of productivity, but just two of them (RA1 and RA2) proved to be hydraulically connected. The wells were equipped with screens for all their drilled depth (100 m), except for the first six meters and some two or three pipes of six meters each, to allow space for the installation for submersible pumps. The length of the installed screens guarantees a good efficiency of the system. In the wells with no connection, the heating system can work using each single well for abstraction and injection, but the process is much less efficient than in the cases where interaction between wells is possible through the rock’s fracture network.