We consider the Cauchy problem for the Perona-Malik equation ut = div ( ∇u 1 + |∇u|2 ) in an open set Ω ⊆ R, with Neumann boundary conditions. It is well known that in the one-dimensional case this problem does not admit any global C solution if the initial condition u0 is transcritical, namely when |∇u0(x)| − 1 is a sign changing function in Ω. In this paper we show that this result cannot be ...

Electrification of the heating sector is a major target energy transition towards more sustainable, efficient, and less polluted future. Heat pumps are considered suitable than electrical heaters or fossil-fueled boilers; however, common refrigerants cause ozone layer depletion, which exacerbates greenhouse effect. Natural refrigerants, such as CO2, perform comparably even better hydrofluorocar...

Blast furnace gas is the major combustible by-product produced in steel industry, where iron ore reduced by coke into iron. Direct combustion of blast after simple treatment for power generation a common utilization method nowadays. However, this suffers from low efficiency and high carbon intensity. The use gas-steam combined cycle an excellent to improve generation. there problem insufficient...

Refrigerant substitution is an urgent need in the context of reducing carbon emissions and slowing global warming. CO2 now being proposed as a promising solution based on its excellent properties system performance, especially low-temperature environments. This paper presents overview recent advances configuration operation characteristics to improve performance transcritical heat pump refriger...

Organic Rankine cycles employing carbon dioxide (CO2) for waste heat recovery became popular in the last years thanks to its excellent transfer characteristics and small environmental footprint. Low-grade (<240 °C) represents major portion of excess globally, but it is hard recover due temperature gap source sink leading a poor efficiency cycle. Therefore, numerous modifications power cycle lay...

Subcooling systems are positioned in recent years as one of the best solutions to improve efficiency transcritical CO2 cycles. Specifically, integrated mechanical subcooling cycle allows improvement these only using a refrigerant. This can be designed with three different architectures: extracting from gas-cooler outlet, subcooler outlet or liquid tank. In this work, configurations experimental...