Thermodynamic analysis and heat exchanger calculations of transcritical high-temperature heat pumps

Heating in industrial processes is responsible for approximately 13% of greenhouse gas emissions in Europe. Switching from fossil-fuel based boilers to heat pumps can help mitigate the effect of global warming. The present work proposes novel high-temperature transcritical heat pump cycles targeted at heating air with a mass flow rate of 10...

A heat transfer - friction analogy for fluids at supercritical pressure

A new friction-heat transfer analogy for the prediction of heat transfer to turbulent fluids at supercritical pressure is presented. This analogy is based on the observation that the predominent events that determine the turbulent heat flux known as hot ejections and cold sweeps have different thermophysical properties. This observation is...

Turbulent heat transfer in channels with irregular roughness

It is well known that rough surfaces affect turbulent flows significantly. How such surfaces affect turbulent heat transfer is less well understood. To gain more insight, we have performed a series of direct numerical simulations of turbulent heat transfer in a channel flow with grit-blasted surfaces. An immersed boundary method is used to...

Turbulence and turbulent heat transfer at supercritical pressure

Numerical simulation of turbulent heat transfer close to the critical point

In this paper we discuss the effect of sharp property variations on the turbulent heat transfer in fluids close the critical point. The governing equations for this flow regime are discussed, a short description of the numerical tools that have been developed to study these flows is given. Finally, some results for supercritical heat transfer in...

Turbulence, heat and mass transfer 2: Proceedings of the second international symposium on turbulence, heat and mass transfer. Delft, The Netherlands, June 9-12, 1997