Borehole modelling: a comparison between a steady-state model and a novel dynamic model in a real ON/OFF GSHP operation

The correct design and optimization of complex energy systems requires the ability to reproduce the dynamic thermal behavior of each system component. In ground source heat pump (GSHP) systems, modelling the borehole heat exchangers (BHE) dynamic response is especially relevant in the development of control strategies for energy optimization purposes. Over the last years, several models have been developed but most of them are based on steady state approaches, which makes them unsuitable for short-term simulation purposes. In fact, in order to accurately predict the evolution of the fluid temperatures due to the ON/OFF cycles of the heat pump, it is essential to correctly characterize the dynamic response of BHE for very short time periods. The aim of the present paper is to compare the performance of an analytical steady-state model, available in TRNSYS environment (Type 557), with a novel short-term dynamic model. The new dynamic model is based on the thermal-network approach coupled with a vertical discretization of the borehole which takes into account both the advection due to the fluid circulating along the U-tube, and the heat transfer in the borehole and in the ground. These two approaches were compared against experimental data collected from a real GSHP system installed at the Universitat Polit ècnica de Val ència. The analysis was performed comparing the outlet temperature profiles predicted by both models during daily standard ON/OFF operating conditions, both in heating and cooling mode, and the between both approaches were highlighted. Finally, the obtained results have been discussed focusing on the potential impact that the differences found in the prediction of the temperature evolution could have in design and optimization of GSHP systems.De Rosa, M.; Ruiz Calvo, F.; Corberán Salvador, JM.; Montagud Montalvá, CI.; Tagliafico, L. (2014). Borehole modelling: a comparison between a steady-state model and a novel dynamic model in a real ON/OFF GSHP operation. Journal of Physics: Conference Series. 547:1-10. doi:10.1088/1742-6596/547/1/012008S11054

Why design history? : A multi-national perspective on the state and purpose of the field

This article asks: what is the significance of design history within higher education? It reviews the practice and purpose of design history, in terms of its role in the education of historically aware and critically engaged designers, as an emerging independent discipline, and in terms of what the subject has to offer allied fields such as history, sociology, cultural studies, area studies and anthropology. It considers the development and current state of design history as it is taught in the UK and wider Europe, the US, Australia, and Japan, China and Korea. The argument that follows is grounded in recent design historical scholarship in order to provide both a contemporary perspective on current practice and suggestions about possible futures.Peer reviewe