77 results about "Natural convection heat transfer" patented technology

The invention relates to a high / low temperature space environment simulating container with a high temperature change rate, comprising a main cabin body, a cabin door, a head sink arranged in the main cabin body, a door sealing structure for connecting the main cabin body and the cabin door, an insulating channel passing through the main cabin body, a sample carrier table, a high / low temperature camera assembly, a high / low temperature fluid stirrer, a temperature measuring system, a pressure measuring system and a vacuumizing structure. A non-high-vacuum environment is formed in the container and is filled with helium; besides radiative heat transfer same as the heat transfer manner of a heat vacuum tank, natural convection heat transfer, even forced convection heat transfer, is added in the cabin, so heat transfer speed is increased greatly, a high / low temperature environment (68K-373K) with a high temperature change rate and even temperature is provided to a sample to be measured. The high / low temperature space environment simulating container is stable, safe and reliable to work.

The invention relates to a method for determining temperature field distribution of a cabin of a carrier rocket in a flight phase in an atmospheric layer. The method comprises a first step of determining an aerodynamic heating thermal flow qh changing along with the flight height and acting on the outer wall of the cabin; a second step of determining an average natural convection heat transfer coefficient alpha n of the shell surface of an instrument in a closed cavity of the cabin changing along with the flight height; a third step of determining a forced convection heat transfer coefficient alpha f of interior of the cabin caused by flight accelerated speed and constant leakage of gas in the cabin; and a fourth step of building a cabin node thermal network model, finishing thermal coupling analysis, and obtaining the cabin temperature field distribution. The method comprehensively considers the impact of aerodynamic heating outside the cabin, air natural convection in the cabin and forced convection on the cabin thermal environment, thereby effectively solving the problem of determination of temperature field distribution of the cabin of the carrier rocket in the flight phase in the atmospheric layer.

The invention discloses a heat-transfer characteristic testing device for a nuclear reactor engineering level dual-layer melting pool. The testing device comprises testing segments, a cover plate, electric heating elements, an insulation board and temperature testing components. The testing device can be used for researching the natural convection heat exchange characteristic of a nuclear reactorengineering level lower dual-layer melting pool (upper metal layer and lower oxidizing-melting pool) in order to get the upward and downward heat-transfer characteristics of the oxidizing-melting pooland the heat-transfer characteristics of a metal layer to a side wall under different working conditions, and analyze the influence of the thickness and height of the metal layer on the heat-transfercharacteristic of the dual-layer melting pool, so that an important basis is laid for the research on the thermal focusing effect of the metal layer. The testing device has the advantages of simple structure, high safety and high operability, and can meet the test requirement for the research on the heat-transfer characteristic of the nuclear reactor engineering level lower dual-layer melting pool.

The invention relates to a reactor simulator, in particular to a uniform inner heat source simulator of a medical isotope production solution reactor, comprising a power simulation part and a fissiongas simulation part, wherein the power simulation part comprises a heating component and a heat exchange component, and the fission gas simulation part comprises a bubble generation device and simulation gas. The invention really reflects power distribution of fuel solution in the reactor, efficiently simulates power distribution of a prototype reactor, strictly controls occupied flow area of an electric heating element without causing great influence on natural convection heat exchange of the solution by the electric heating element, solves the problems of high simulation power and small cross section of the electric heating element in the prior art and satisfies the experimental requirements. In addition, nitrogen gas is used as the simulation gas so that the safety of an experiment is ensured.

The invention provides a radiant air conditioner indoor unit, an air conditioning system and a control method. The radiant air conditioner indoor unit comprises a radiant panel and a microchannel heatexchanger. The radiant panel is attached to the side face, facing indoors, of the microchannel heat exchanger. According to the radiant air conditioner indoor unit, the air conditioning system and the control method provided by the invention, by arranging the microchannel heat exchanger and the radiant panel, radiant heat exchange and natural convection heat exchange can be achieved, the user comfort is improved, in addition, by arranging the radiant panel, the radiation efficiency and comfort can be improved, the appearance of the microchannel heat exchanger is beautified, the mounting and later maintaining difficulty is lowered, due to the fact that a coolant is directly introduced into a room, the temperature range for heat exchange is enlarged, by arranging a thermal infrared imager and an image collecting device, the frequency of a compressor and / or the opening degree of an adjusting valve can be intelligently adjusted according to the detected indoor temperature, body temperature of a user and physical state of the user, the purpose of intelligent control is achieved, and by arranging a second heat exchanger, the radiant heat exchange efficiency is improved.

The invention discloses a method and an experimental device suitable for measuring the heat conductivity coefficient of flowing high-temperature high-pressure fluid. The experimental device comprises a test tube, a heating copper electrode A, a heating copper electrode B, a temperature measuring mixed cavity A, a temperature measuring mixed cavity B, a wall temperature thermocouple, a fluid temperature thermocouple A, a fluid temperature thermocouple B, a copper electrode lead A, a copper electrode lead B, a switchover tee joint A and a switchover tee joint B, and also comprises a heat shielding screen and a thermal insulation material wrapping the outer wall of the test tube. According to the experimental device, the test tube can be well subjected to heat insulation, so that loss of natural convection heat exchange and radiant heat can be effectively reduced in experiment, the experiment date error is small, and effective basis is provided for accurate experiment data of the heat conductivity coefficient and design and application of the heat conductivity coefficient. The experimental device provides effective help for research of a novel cooling manner, and also provides experimental feasibility for accurate experimental measurement of the heat conductivity coefficient of the high-temperature high-pressure fluid under pressure of 0-7MPa.

The invention discloses a hog house fresh air, temperature and humidity regulation and control system. The hog house fresh air, temperature and humidity regulation and control system comprises a roof, a plastic film greenhouse, a supporting member, a fermentation bed and a platform, wherein periphery of a hog house is enclosed by brick walls, the wall of the hog house is provided with a wall interlay air channel, the connection portion of the wall interlay air channel and the hog house is provided with an air supply outlet, the upper portion of the hog house comprises the roof, the supporting member and the plastic film greenhouse, the upper portion of the plastic film greenhouse is provided with a sunshading screen cloth, the roof is provided with an electrical air exhaust port and an axial-flow blower fan, a shady face wall of the hog house is provided with a ventilation window, the fermentation bed and the platform are at a central position of the hog house, soil below the fermentation bed and the platform is provided with heat exchange air channels, and ground portions of the heat exchange air channels are provided with air inlets and filter nets. A summer air exchange and heat radiation process is a natural convection heat exchange process, forced mechanical air exhaust is not necessary, outdoor hot air is cooled and dehumidified through the ground soil and is then sucked into the hog house, fresh air exchange is further realized, no energy consumption is realized in the process, and the cooling effect is excellent.

The invention relates to a device for measuring a heat conductivity coefficient of liquid on the basis of a transient plane source method and relates to a measurement device for the heat conductivity coefficient. The invention aims to solve the problem that when an existing transient plane source method is adopted to measure the heat conductivity coefficient of the liquid, a probe is vertically placed, natural-convection heat transfer is formed on the surface of the probe and adoption of low output power can cause increase of a data dispersion ratio and causes an excessively high measurement result of the heat conductivity coefficient of the liquid. The device comprises a computer, a sample holder, a valve, a sample bin, a solid standard sample, a probe, a gasket, aluminum alloy and a liquid pool; the sample holder is arranged in the sample bin; the aluminum alloy is arranged on the sample holder; the liquid pool is formed at the upper end of the aluminum alloy; the gasket is arranged on the upper end face of the liquid pool; the solid standard sample is arranged on the upper end face of the gasket; the lower end face of the solid standard sample is provided with a groove with a depth of 25 micrometers; the probe is arranged inside the groove with the depth of 25 micrometers. The device provided by the invention is capable of measuring the heat conductivity coefficient of the liquid on the basis of the transient plane source method.

The invention relates to the technical field of refrigerators, in particular to a spaceflight low temperature refrigerator. The spaceflight low temperature refrigerator comprises a Stirling refrigerating system, a box body and a heat conducting system. The refrigerating system comprises refrigerating equipment, a refrigerating capacity channel and an electric control part; the box body comprises ashell, a thermal isolating layer, a door and an inner container; the heat tube heat conducting system comprises a heat conducting backboard, multiple heat tubes, a heat conducting clapboard, a heat conducting drawer and a heat conducting graphite membrane. The problems that when a Stirling refrigerating refrigerator is applied to a spaceflight space station and a shuttle, in the absence gravity effect, since air in a box cannot generate natural convective heat transfer, the temperature difference in the refrigerator is large, and scientific research requirements cannot be met. The spaceflightlow temperature refrigerator is particularly applicable to the situation that since temperature is too low, a fan cannot be installed in the box.

The invention provides a double-side strengthened heat transfer smoke tube of a vertical gas-fired hot water boiler. The double-site strengthened heat transfer smoke tube is characterized in that the smoke tube is sleeved with a longitudinal corrugated fin and a blind tube with a spiral sheet is arranged in the smoke tube. The longitudinal corrugated fin is formed by bending and welding a thin steel plate which is repeatedly folded according to the width half of the space of the smoke tube. The outer wall face of the smoke tube is tightly sleeved with the whole corrugated fin by high-frequency welding, the heat-transfer area of the outer side of the smoke tube can be remarkably increased, and therefore natural-convection heat transfer of water outside the smoke tube is reinforced. After the blind tube is wound by the spiral sheet, the blind tube and the spiral sheet are integrally inserted into the smoke tube and fixed, the smoke flow area is reduced through the blind tube, the smoke flow speed is increased, spiral flow of smoke is generated by the spiral sheet, the smoke flow path is lengthened, and convection heat transfer of the smoke and the wall face of the smoke tube is reinforced. The double-side strengthened heat transfer smoke tube is simple in structure, convenient to manufacture and capable of reinforcing convection heat transfer between the smoke and water, decreasing the smoke discharging temperature of the boiler and effectively improving the heat efficiency of the boiler.

The invention provides an LED radiator. The LED radiator comprises an inner cavity, fins and a light source mounting surface, wherein the light source mounting surface is in contact with the side surface of the barrel wall of the inner cavity; the LED light source is arranged on the surface of the light surface mounting surface; the fins are spaced in a fan-shaped mode outside the barrel wall of the inner cavity from the two sides of the light source mounting surface by taking the barrel wall of the inner cavity as center; directions of ripples at the two sides of each fin are reverse; directions of ripples opposite to every two adjacent fins are reverse; and the inner cavity is injected with phase-change heat conduction liquid. The LED radiator achieves better radiating effect by increasing a natural convection heat exchange coefficient of fins-air, further realizes a compact structure, lower cost and high efficiency, and is especially suitable for the LED light source with large power and high heat flux.

The invention discloses a heater for a bulk curing barn, which comprises a heating furnace and a heat exchanger. A furnace top heat radiating fin is arranged on a furnace top gland; a secondary air inlet passage for negative-pressure combustion is arranged on the outer wall of a furnace body; the heat exchanger comprises a left fire box, a right fire box and a heat exchange pipe which is positioned between the two fire boxes and communicated with the fire boxes; a bracket and a smoke passage which is communicated with an inner cavity of the furnace body are installed on the furnace top gland;a fin is arranged on the outer wall of the smoke passage; the bracket is supported under the left fire box of the heat exchanger; and the right fire box of the heat exchanger is communicated with theinner cavity of the furnace body through the smoke passage. The heater disclosed by the invention not only has a compact structure but also has the natural convection heat exchange efficiency of reaching more than 44 percent and the ventilating heat exchange efficiency of reaching more than 47 percent; the equipment is provided with a dust removing device, reduces the accumulated dust on a heat radiating pipe and is provided with a positive-pressure combustion-supporting fan, a negative-pressure combustion-supporting fan and a proper chimney; accordingly, compared with the traditional heater,the heater has good heat exchange effect and improves the precision of temperature control.

A heat transfer test device of air natural convection for large space external pipe consists of external pipe headstock, control and collection analyzer and computer. It is featured as forming said headstock to be frame structure in rectangular solid shape, hanging the heating external pipe with thermocouple at its surface on horizontal beam of headstock, connecting thermocouple to control and collection analyzer and computer for realizing real time detection.

The invention provides a testing system and method for heat-transfer properties of an engineering magnitude-order double-layered molten pool of a nuclear reactor. The system comprises a main loop composed of a water storage tank, a testing section, a main water pump and a related pipeline valve, a cooling loop composed of a cooling tower, an auxiliary water pump, a heat exchanger and a related pipeline valve, a molten salt loop composed of a molten salt furnace, a vacuum pump and a related pipeline valve, a heat-conducting oil loop composed of a heat-conducting oil tank, a recycling groove anda related pipeline valve, a heating module, a data measurement and acquisition module, an image acquisition and analysis module and a control module; the invention further provides the testing methodof the system. According to the testing system and method, a natural convection heat exchange test of the double-layered structural molten pool (an upper metal layer and a lower oxidization molten pool) of the nuclear reactor under a severe accident is carried out to obtain upward and downward heat-transfer properties of the oxidization molten pool and the heat-transfer properties of a side wallof the metal layer, and reference can be provided for engineering practice and application of a reactor core melt retention technology (IVR).

A method for estimating the instantaneous heat generation rate of a pouch cell comprises the following steps: (1) measuring temperature rise-per-second data of a cell at a charge / discharge rate in an adiabatic environment, and calculating the storage heat generation power per second q1 of the cell under the rate condition; (2) measuring static temperature drop data of the cell at the end of the charge / discharge rate in the adiabatic environment, and getting the natural convection heat transfer coefficient h in the environment through curve fitting; (3) calculating the corresponding natural convection loss power per second q2 in the charge / discharge process in the environment according to the natural convection heat transfer coefficient h and the temperature rise-per-second data in the adiabatic environment; and (4) adding the storage heat generation power per second q1 and the natural convection loss power per second q2 together to get the heat generation power per second under the condition, and getting the instantaneous heat generation rate through polynomial fitting according to the heat generation power per second. Through the method, the heat generation rate of a pouch cell in the charge / discharge process can be easily calculated. The method is of certain value to the study on performance of cells in the charge and discharge process.

The invention provides an LED lamp with an optimized radiating fin dimension and structure according to the natural convection heat transfer basic experiment research results aiming at fin-type structures, which points out that the ratio of the height h of fins to the gap a between the fins is not more than 10.0, and the gap a is not less than 1.7mm. The heat dissipating capacity is further increased by additionally installing a convection shield (4), and thereby, the level that the aluminium consumption of heat dissipation per watt is less than 4g can be achieved. In order to realize standardization, a radiating fin is separated from an LED lampwick comprising an LED core (1) and a heat conduction core (12), wherein the radiating fin is a component fixed in a light fitting, and a specific scheme for solving the heat transfer problem between the heat conduction core (12) and the radiating fin is proposed.

A special-shaped fin structure design method for strengthening natural convection heat exchange comprises the steps that firstly, a physical model of a natural convection heat exchange problem is determined, according to the actual fin structure design problem based on natural convection heat exchange, a domain to be analyzed and geometric and physical conditions are extracted, and the physical model suitable for topological optimization is established; a finite body analysis model of the base structure is established; an optimization model of the special-shaped fin structure is established; an optimization model driven by a physical field is established by adopting a topological optimization method described by a variable density method to minimize a uniform temperature target function ata heat source, and the optimization direction of each time is determined; then iterative optimization of the special-shaped fin structure is carried out, and the optimized special-shaped fin structure is obtained; and finally, the optimized special-shaped fin is subjected to smoothing and rounding treatment. According to the method, the design experience is not needed, the complex design, simulation and improvement redesign process is not needed, the obtained special-shaped fin structure can fully strengthen the natural convection heat exchange effect, and the optimal cooling effect is achieved.

The invention discloses a metal reflective warming plate. The metal reflective warming plate comprises a thermal insulation casing and several stacked metal reflection foil sheets coated with the thermal insulation casing. Each one of the several stacked metal reflection foil sheets is provided with several raised first ribs arranged along a first direction and several raised second ribs arranged along a second direction, the first ribs and the second ribs are staggered and extend to form several rhombic unit arrays, the rhombic units of each two adjacent metal reflection foil sheets form an included angle of 90 degrees, the raised first ribs and second ribs of each two adjacent metal reflection foil sheets are staggered oppositely, and several relatively-independent air sandwich chambers are formed between each two adjacent metal reflection foil sheets. The metal reflective warming plate utilizes the metal reflection foil sheets of the rhombic unit structures, and the air layer between each two adjacent metal reflection foil sheets is divided into narrow spaces so that air natural convection heat transfer between the metal reflection foil sheets can be effectively inhibited.

The invention provides a heat treatment method for obtaining the two-way shape memory effect of an SMA (Shape Memory Alloy) material. The method comprises the following steps of: stretching, bending or twisting the SMA material and keeping the shape of the stretched, bent or twisted SMA material unchanged; then heating metal on the surface layer of the SMA material by a high frequency induction heating coil and controlling a certain heating temperature and heat preservation time; and relieving the restriction at both ends of the SMA material so as to cool the SMA material under the condition of room temperature natural conversion heat exchange. The surface layer and an inner layer of the SMA material processed by the method have different crystal structures; the inner layer has low temperature in the heating process, the crystal structure of the inner layer is basically unchanged, and the inner layer shows the shape memory effect and is used as a driving material; the surface layer has high temperature in the heating process, the crystal structure of the surface layer is changed, and the surface layer shows superelasticity and is used as an elastic recovery material; the surface layer and the inner layer are matched to form the two-way shape memory effect; a prepared double-way SMA driving component has a simple structure and compact size and is very suitable for being used as a driving component in a driver.

The invention relates to the field of electric heater equipment, in particular to a heat dissipation type electric heater. The heat dissipation type electric heater comprises a cavity body and an electric heating element, wherein the electric heating element is arranged in the cavity body. The heat dissipation type electric heater is characterized in that heat dissipation fins are arranged in the cavity body, and conduction oil is poured between an inner shell and an outer shell of the cavity body; an insulating layer is arranged between the electric heating element and the outer shell of the cavity body, and a temperature control element is arranged in the cavity body and connected with the electric heating element in series; the electric heating element is composed of a plurality of heating rods, and the heating rods are connected in parallel; a temperature regulating knob is arranged at the upper end at the outer part of the cavity body, and a small wheel is arranged at the outer end at the bottom of the cavity body; a plurality of through holes are formed in the surface of the outer shell of the cavity body. The heat dissipation type electric heater has the advantages of being good in natural-convection heat transfer effect, fast in heating, high in thermal safety and convenient to move.

The invention relates to a heat exchanger, in particular to a heat pipe type heat exchanger for a heat pump water heater. The heat pipe type heat exchanger comprises a hot water tank and a refrigerant box, wherein the refrigerant box is arranged on the lower side, the hot water tank is arranged on the upper side, and the refrigerant box is mutually isolated from the hot water tank and is not communicated with the hot water tank; a plurality of inverted U-shaped tubes are arranged in the hot water tank; the lower tube orifices of the inverted U-shaped tubes are communicated with the refrigerant box; the hot water tank is provided with hot water; a heat exchanging coil is arranged in the refrigerant box; the refrigerant box is vacuated; and the refrigerant box is provided with a secondary refrigerant. The secondary refrigerant, a refrigerant and the hot water transfer heat in a forced convection mode, so that the efficiency is greatly higher than that of natural convection heat transfer, the used heat exchanging materials can be reduced, the volume of the hot water tank is reduced, the temperature difference of heat transfer can be reduced, and the energy efficiency ratio of a system is improved. Meanwhile, the heat exchanging coil is arranged in the refrigerant box, so that the risk that the refrigerant in the heat exchanging coil directly leaks into the hot water is low, and the heat exchanger is more safe and reliable.

The invention discloses a cloth odor elimination device which is composed of a shell, a water tank, vibration motors, a supporting rod and a ventilation device. The water tank is arranged at the bottom inside the shell. A plurality of water vapor outlets are machined in a cover plate of the water tank in parallel. A temperature adjusting heating device is arranged inside the water tank. During heating, the shell is full of water vapor; the supporting rod above the water tank is used for suspending clothes with odor to be removed; the two ends of the supporting rod are connected with the vibration motors at the corresponding ends respectively, the vibration motors drive the supporting rod to vibrate, the clothes are sufficiently spread in the vapor steaming process during vibration, and the contact area is increased. Due to usage of distilled water containing no chemical reagent, the clothes are placed into the environment with large humidity and high temperature, and odor is rapidly removed; an air drying ventilation device for reinforcing natural convection heat transfer is adopted, natural convection heat transfer is reinforced, the clothes can be rapidly dried in air after vapor is ended, and the clothes will not be damaged by excessively high temperature. The cloth odor elimination device is simple in structure, and convenient to use and operate.

The invention discloses a method for researching thermal characteristics of a static pressure rotating worktable under extreme conditions. A relationship among flow, bearing capacity and oil film thickness of a dual rectangular cavity oil pad structure is subjected to theoretical derivation. The heat emission coefficients of the worktable under different extreme conditions are calculated out by applying a heat conduction theory; and the calculation of a convective heat transfer coefficient of the rotating worktable can be divided into the calculation of an upper surface and a side surface, namely, the calculation of a convective heat transfer coefficient of the upper surface can be likened to that a fluid flows through a horizontal plate, and the calculation of a convective heat transfer coefficient of the side surface can be likened to that the fluid transversely skims over a vertical plane wall. An area trisection method is proposed; the convective heat transfer coefficient of each part of the upper surface of the rotating worktable is calculated; and finally a mean value is calculated to serve as the convective heat transfer coefficient of the rotating worktable. A base is divided into two parts, namely natural convective heat transfer of the surface of the vertical plane wall and natural convective heat transfer coefficient of the horizontal plate with a downward hot surface, and the convective heat transfer coefficients are calculated. Finally the overall deformation of the worktable and the base is solved by taking a temperature field and a pressure field of an oil film as body loads.

The invention provides a high-efficiency and high-precision measurement experimental device for a natural convection heat transfer coefficient. The device comprises a unit-pipe pipe wall, a primary heating rod, an auxiliary heating rod, an insulating sheet, a heat-insulation jacket, heat-isolation end covers, a film thermocouple, terminal sleeves, an A / D (Analog / Digital) converter, a computer, a control box and a bracket. The insulating sheet is inserted between the primary and auxiliary heating rods of the device to form close connection; pipe cavities at an effective experimental section and an auxiliary experimental section which are corresponding to the primary and auxiliary heating rods respectively are spaced by using the annular heat-insulation jacket; the temperatures of the adjacent terminal sleeves of the primary and auxiliary heating rods are controlled to be the same through regulating the current and the voltage of the auxiliary heating rod, so as to reduce the axial heat loss of the primary heating rod; the internal surface silvered heat-isolation end covers are sleeved at each unit-pipe port; high-temperature-resistant heat-isolation foam mats are filled in gaps among the heat-isolation end covers and unit pipes, so as to reduce the heat loss due to radiation at an auxiliary-section port; the external surfaces of the unit pipes are slivered, and the internal surfaces of the unit pipes are plated with high-radiance materials, so as to shorten an experimental time. The measurement problem of the natural convection heat transfer coefficient is solved highly efficiently and highly precisely.

The invention relates to a method for calculating the convective heat transfer coefficient of a hydrostatic rotary table. The method comprises the steps of calculating convective heat transfer coefficients of the rotary table and a base, wherein the calculation of the convective heat transfer coefficient of the rotary table can be divided into two parts: the calculation of the upper surface and the calculation of side faces, that is, the calculation of the convective heat transfer coefficient of the upper surface can be compared to fluid flowing through a horizontal plate and the calculation of the convective heat transfer coefficient of the side faces can be compared to the fluid horizontally flitting through vertical planar walls; the convective heat transfer coefficient of each part ofthe upper surface of the rotary table is calculated by using an area trisectioning method, that is, the rotary table has a large radius and the heat emission coefficients at different positions at thesame rotation speed have large differences, so that the upper surface of the rotary table is divided into three parts and the average value is calculated through averaging to serve as the convectiveheat transfer coefficient of the rotary table; and the convective heat transfer of the base is divided into two parts: the natural convective heat transfer of the vertical planar wall surface and thenatural convective heat transfer of the horizontal plates, hot faces of which are downwards arranged, to calculate the convective heat transfer coefficient of the base.

Disclosed is a natural heat dissipation apparatus of an electronic device. The heat dissipation apparatus consists of a substrate, and heat dissipation fins and a back shell arranged on the substrate; the heat dissipation fins adopt a W-shaped structure and are arranged perpendicular to the substrate, and the corners of the fins are subjected to interruption treatment; the back shell is manufactured by an insulating material, and is tightly attached to the back part of the substrate; in the working process, the heat dissipation apparatus is perpendicularly arranged; heat generated by the electronic device is transferred from a heat pipe to an aluminum flat plate; the aluminum flat plate is placed in the back shell and then is laminated with the substrate of the heat dissipation apparatus; and finally, heat is dissipated to the environment through the W-shaped heat dissipation fins. By virtue of the specific arrangement mode of the W-shaped heat dissipation fins, the heat dissipation area is enlarged, the contact flow between gas and the fins is reduced, the air inlet amount in the horizontal direction is greatly increased, the heat exchange temperature difference is increased, and natural convection heat exchange efficiency is improved, thereby prolonging the service life of the electronic device and improving reliability of equipment.

The invention discloses a heat transfer strengthening device for natural convection heat dissipation and a design method thereof. The heat transfer strengthening device comprises an auxiliary heat dissipation wall fixedly disposed on the surface of a device to be cooled. The auxiliary heat dissipation wall and the surface of the device to be cooled constitute a cylindrical ventilation passage. Thecross-sectional area of the cylindrical ventilation passage remains unchanged or gradually decreases along the flow direction of an air flow. The auxiliary heat dissipation wall is provided with a plurality of vents. The heat transfer strengthening device of the invention can be applied to the surface of a device based on natural convection heat transfer, can improve an air natural convection heat dissipation effect, can retard sunlight irradiation, and can reduce the surface temperature of the outdoor device to be cooled. The auxiliary heat dissipation wall can avoid the direct radiation ofthe sunlight to the surface of the device to be cooled, thereby reducing the total amount of heat dissipation of the device. The cylindrical ventilation passage can form a chimney suction effect to effectively increase the natural convection velocity of the air near the surface of the device to be cooled, so as to strengthen the heat transfer.

The invention discloses a center furnace liner L-shaped guide pipe vertical gas boiler. The center furnace liner L-shaped guide pipe vertical gas boiler comprises a combustor, a cylinder, a furnace liner, L-shaped guide pipes, smoke collecting boxes, smoke pipes, a spiral guide piece, smoke transfer chambers, a water inlet pipe, a water outlet pipe, a smoke discharge pipe, a support pipe and a base, and is characterized in that the combustor is positioned at the top end of the vertical boiler cylinder; the furnace liner is positioned in the center position of the vertical boiler; multiple L-shaped guide pipes are arranged in the furnace liner, and form a center radial shape; the upper ends of the L-shaped guide pipes penetrate through the wall surface of the middle part of the furnace liner to weld with the wall surface, and the lower ends penetrate through a baseplate of the smoke transfer chamber to weld with the baseplate; the smoke pipes are arranged around the furnace liner; the smoke collecting boxes are respectively connected to the upper ends of the smoke pipes and the furnace liner; and the smoke transfer chambers are respectively connected to the lower ends of the smoke pipes and the furnace liner. Smoke radially exchanges heat with the furnace liner and the L-shaped guide rails to increase the radial heat exchange area; and furnace water in the L-shaped guide pipes is heated to quickly flow upwards, so that the natural convection heat exchange of the furnace water is reinforced, and the circulation of water in the furnace is quickened. The boiler is compact in structure, larger in heat exchange area and higher in heat efficiency.

The invention relates to the technical field of air conditioners, in particular to a vehicle air conditioning system which comprises a compressor, an out-vehicle heat exchanger, a throttle valve and an in-vehicle heat exchanger which are sequentially connected to form a closed circulation loop, the compressor is connected with the in-vehicle heat exchanger and the out-vehicle heat exchanger through the four-way valve. The two sides or the peripheral wall of an air inlet of the in-vehicle heat exchanger are arranged to be inclined air guide faces, and the inclined air guide faces form a flaringshape. And a forced convection part is not arranged on the out-vehicle heat exchanger. The invention has the following effects: 1, natural convection heat exchange is adopted outside the vehicle, andnatural convection heat exchange is mainly adopted inside the vehicle, so that the noise is obviously lower; 2, natural convection heat exchange is adopted outside the vehicle, and natural convectionheat exchange is mainly adopted in the vehicle, so that the energy-saving effect is remarkable, and the comfort is high; and 3, compared with a traditional bus air conditioner, an outer fan is omitted, an inner fan is also used less, and other parts are all common mature materials, so that operation is stable and reliable, and control, maintenance and management are convenient.