The disclosure relates to a fuel filter assembly, a filter element, and a method of draining water from a fuel filter assembly. The fuel filter assembly comprises a filter element with a water collecting space; the filter element being connected to a fuel pipe for feeding an upstream side of the filter element with fuel and for providing filtered fuel from a downstream side of the filter element to a combustion engine or parts thereof; a fuel pump arranged downstream from the filter element, wherein the fuel pump can be operated in a first mode for drawing fuel through the filter element and in a second, reverse mode for feeding fuel back to the filter element; a one-way fuel valve arranged upstream of the filter element allowing for flow towards the upstream side of the filter element; a pressure-actuated one-way drain valve in communication with the water collecting space.

A system for preparing nanoparticles by supercritical hydrothermal synthesis is provided. Firstly, a mixture of a first reactant and a second reactant and high-temperature water at an outlet of a heating furnace (10) are mixed and are heated to a reaction temperature, the mixture is connected to a supercritical hydrothermal synthesis reactor (14), and a product at an outlet of the supercritical hydrothermal synthesis reactor enters a heat regenerator (9); hot water at an outlet of a low-temperature section of the heating furnace (10) first enters the heat regenerator, and then enters a high-temperature section of the heating furnace so as to be continuously heated to a set temperature; fluid at the pipe side outlet of the heat regenerator separately passes through a heat exchange coil in a first reactant modulation pool (1) and a steam generator (2) in a waste heat power generation system (20).

A multifunctional filter valve is provided. The multifunctional filter valve includes a valve body, a rotatable valve plate, a fixed valve plate, and a driving device. A water inlet, a water outlet, and a drainage outlet are disposed on a side wall of the valve body. The water outlet is configured to connect to a valve. An inner chamber and an outer chamber are defined in the valve body. The inner chamber defines a central drainage chamber, a working chamber, a backward washing chamber, and a blind chamber. A first filter element interface and a second filter element interface are defined at a bottom of the valve body. The combination of fixed valve plate and rotatable valve plate achieves a normal operation mode, a backward washing mode, and a forward washing mode. The multifunctional filter valve has a simpler structure and lower production cost.

The invention relates to a filter insert for a fluid filter device, comprising: a) a first circumferential filter element comprising a first folded filter medium, b) a second circumferential filter element comprising a second folded filter medium, c) a first base element and a second base element, and d) a cover element with a fluid outlet, wherein the first filter element, the first base element, and the cover element form a first inner chamber, said second filter element being arranged in the first inner chamber, and the second filter element, the second base element, and the cover element form a second inner chamber, wherein the filter insert is designed so that a fluid to be filtered can flow from the outside through the first filter element into the first inner chamber, from the first inner chamber through the second filter element into the second inner chamber and out of the second inner chamber through the fluid outlet, The quotient of the filter surface area of the first filter element divided by that of the second filter element is greater than one, the quotient of the filter rating of the first filter medium divided by the filter rating of the second filter medium equals one or more, and the first filter medium and the second filter medium have a bending strength of 2.5 N*mm.sup.2 or more according to DIN 53864:1978-08.