Many researchers have investigated how to increase the overall efficiency of solar-driven thermal systems. Several key parameters, such as collector efficiency and storage tank characteristics, may impose some constraints on the annual solar fraction (ASF) of such systems. In this paper, the behaviour of integrating the phase change material (PCM) in SDHW systems is modelled and optimized n...

The thermal stratification of the upper water layers in the Baltic Sea varies seasonally in response to the annual cycle of solar heating and wind-induced mixing. In winter, the stratification down to the halocline is almost completely eroded by convection and strong wind mixing. Monthly averaged temperature profiles obtained from the ICES hydrographic database were used to study the long-term ...

The effects of exponentially varying viscosity and linearly varying thermal conductivity on unsteady MHD natural convective flow past a semi infinite vertical plate in a thermally stratified medium is studied. The variables of both viscosity and thermal conductivity are considered only a function of temperature. The governing boundary layer equations of continuity, momentum and energy have been...

We measured under-ice thermal stratification from before ice-on through after ice-off in Lake Sunapee, New Hampshire, a large, deep, north temperate lake, using a high-frequency monitoring buoy in the winter season of 2007–2008 to quantify how lake thermal stratification varies throughout the under-ice season. We examined potential drivers of variation in under-ice stability, identified diel-sc...

It is generally held that atmospheric macroturbulence can be strongly nonlinear. Yet weakly nonlinear models successfully account for scales and structures of baroclinic eddies in Earth’s atmosphere. Here a theory and simulations with an idealized GCM are presented that suggest weakly nonlinear models are so successful because atmospheric macroturbulence organizes itself into critical states of...

This semester project investigates strategies aimed at controlling the aggregate power demand of large groups of domestic electric water heaters. An existing model of a single electric water heater that considers thermal stratification along the height of the hot water tank was tuned and verified using experimental data. The tuned model was then incorporated into an existing model of a water he...

In lentic freshwater ecosystems, patterns of thermal stratification play a considerable part in determining the population dynamics of phytoplankton. In this study we investigated how these thermal patterns and the associated hydrodynamic processes affect the vertical distribution of phytoplankton during two consecutive diel cycles in a warm polymictic urban reservoir in the metropolitan region...

Forced stratified flows are shown to suffer two types of linear long-wave instability: a ‘viscous’ instability which is related to the classical instability of Kolmogorov flow, and a ‘conductive instability’, with the form of a large-scale, negative thermal diffusion. The nonlinear dynamics of both instabilities is explored with weakly nonlinear theory and numerical computations. The introducti...