A heat pump is an electrically-ponered refrigerationcycle device which is capable ofproviding both heating and cooling to a residence. In the sumrrcr, it operates like an air conditioner by "moving" heat from inside the house to the outside. In the winter, the refrigerant flow is reversed, "moving" heat into the house by further chilling the already cold outside air and transferring the heat ga...

Fourier theory of thermal transport considers heat transport as a diffusive process where energy flow is driven by a temperature gradient. However, this is not valid at length scales smaller than the mean free path for the energy carriers in a material, which can be hundreds of nanometres in crystalline materials at room temperature. In this case, heat flow will become 'ballistic'--driven by di...

An irreversible cycle model of a Braysson heat engine operating between two heat reservoirs is used to investigate the thermoeconomic performance of the cycle affected by the finite-rate heat transfer between the working fluid and the heat reservoirs, heat leak loss from the heat source to the ambient and the irreversibility within the cycle. The thermoeconomic objective function, defined as th...

This paper investigates the interface temperature rise in polishing a polycrystalline diamond (PCD) surface. First, the Greenwood– Williamson’s statistical asperity model is applied to characterise the surface roughness of a PCD specimen. The result is then used to estimate the contact area and total number of contact asperities under an applied polishing load. The heat generated is taken as th...

This paper investigates the feasibility to achieve grinding-hardening in a plunge cylindrical grinding process. To understand the mechanisms, a temperature-dependent finite element heat transfer model incorporating a triangular moving heat source was developed to describe the temperature field, thus to predict the thickness of the grinding-hardened layer. The analysis carried out included the v...