70results about How to "High specific heat" patented technology

An improved cold / compress therapy for the treatment of muscle, tissue, tendon, or cartilage injury or damage. The ICE Power Pack consists of a plurality of hollow vessels filled with water or aqueous solutions or colloids that can be solidified in a conventional domestic or commercial freezer. The encapsulated water or aqueous solutions or colloids rely on the high latent heat of fusion as they undergo a phase change providing an extended therapeutic period in a medically safe temperature zone. The vessels are sandwiched between flexible insulating and non-insulating layers that serve as compresses.

The invention relates to a fire-retardant type wide-frequency-band high-power compound wave-absorbing material and a preparing method thereof. The material comprises an outer shell, an inner core and a base, wherein the outer shell is a polyhedron formed by a set of pyramids arranged side by side, the wedges of the pyramids are towards the same side, the inner core is located inside the outer shell, the base is located at the bottom of the outer shell, the outer shell is made of non-woven cloths, the inner core and the base are made of polyurethane foams, the inner surface and the outer surface of the outer shell are respectively provided with a first fire-retardant wave-absorbing agent layer in a coating mode, and the inner core and the base are immersed in second fire-retardant wave-absorbing agents. Both the first fire-retardant wave-absorbing agents and the second fire-retardant wave-absorbing agents comprise acetylene black, alpha-SiC, aluminum hydroxide, kaolin, pentaerythritol, and App-3. The corresponding preparing method comprises the steps of preparing the outer shell, preparing the inner core and the base, and inserting the inner core into the outer shell, and therefore the wave-absorbing material is obtained. The wave-absorbing material has good wave absorbing performance and fire retardance, and the preparing method is simple and easy to implement.

A heat dissipating device includes a heat sink (10), a heat pipe (20), a heat reservoir (30) thermally connecting with the heat sink through the heat pipe, and a fan (40) generating an airflow through the heat sink. The heat pipe includes an evaporating portion (202) attached to the heat sink and a condensing portion (204) attached to the heat reservoir. The heat reservoir is made of metal containing working medium, such as water, therein. The heat reservoir stores or releases heat based on the amount of heat generated by the CPU to realize a compensation to the increase or decrease of temperature of the CPU, whereby the change rate of the temperature of the CPU from idle to busy condition and vice versa can be more stable.

The invention relates to viscosity-controllable aqueous lubricating liquid and application. The viscosity-controllable aqueous lubricating liquid consists of triethanolamine borate, triethanolamine oleate, triethanolamine sebacic acid, an alcohol viscosifier, an organic silicon defoaming agent and water. The viscosity range is from 0.9 Pa.s to 8 Pa.s. The main component of the water-based lubricating liquid is water, so excellent characteristic, such as fire resistance, of the water and high specific heat are preserved; each component of the aqueous lubricating liquid has low price, no toxicity and high degradability and meets the requirements of environmentally-friendly lubricants; tests show that the aqueous lubricating liquid has high rust resistance; an anti-rusting agent component ofthe aqueous lubricating liquid comprises a polar group with a large adsorption force, so the aqueous lubricating liquid has anti-friction and anti-wear effects on a friction pair and prolongs the service life of equipment; and the viscosity of the lubricating liquid can be adjusted by changing the viscosifier content according to specific engineering requirements, so that the higher rigidity, bearing capacity and heat stability of a processing equipment main shaft and a hydrostatic guideway system are guaranteed.

The invention discloses a heat transfer medium special for a solar heat pump and a preparation method thereof, which belong to renewable energy source utilization technology. The heat transfer medium is prepared by mixing, heating and stirring ethylene glycol, ionized water, triethanolamine, sodium dihydrogen phosphate, sodium benzoate, phosphoric acid, tolyltriazole styrene, borax, a defoaming agent, an inhibitor and a color concentrate in different weight ratios. The transfer medium has the characteristics of low freezing point, freeze prevention, high low-temperature flowing property, high boiling point, low evaporation loss, high specific heat, high heat conductivity, less foam, high anti-foam performance, and good anti-rust protection and descaling functions for metal pipelines.

The invention provides a waste gas pollutant combined removal device for a two-stroke diesel engine. The waste gas pollutant combined removal device comprises a waste gas washing device and a recirculation waste gas flow control device, the waste gas washing device comprises a washer, a washing solution storage box, a circulation pump, a SOx absorbing agent supply device and a fresh waste supply device, and the recirculation waste gas flow control device comprises a flow regulating valve, a recirculating draught fan and a one-way control valve. According to the waste gas pollutant combined removal device, waste gas of the two-stroke diesel engine is washed, the SOx content and the particle content in the waste gas are reduced, part of low-temperature clean waste gas is recirculated, the NOx generation amount of the engine is reduced, and combined desulfurization and denitration of waste gas pollutants of the ship diesel engine is achieved. According to the waste gas pollutant combined removal device, part of washed waste gas is recirculated, the combustion condition in a cylinder is improved to a large extent,by CO2 and vapor contained in the low-temperature clean waste gas and the NOx generation amount and the final discharge amount of the engine are reduced.

The invention discloses a thermal-radiation internal-circulation power generation device, which is mainly composed of a solar energy tube (5), three high-position expansion grooves (6-1, 6-2 and 6-3), a low-position oil storage tank (25), three circulation pumps (8-1, 8-2 and 8-3), an energy storage tank (7), a constant temperature furnace (12), a water coagulation expansion tank (10), a high pressure pour plug pump (13), a high pressure atomizing device (14), a steam generator (15), a steam storage tank (18), a turbine (19), a generator (20), a circulation steam pipeline (21), a steam coagulator (22) and a coagulation water pipe. The thermal-radiation internal-circulation power generation device can fully use a solar energy heat source and a saline solution as stored energy and a heat transfer medium and uses other energy to heat in complementary mode. The steam generator is of a special structure, and atomized wet air flow is heated by heat conduction oil to be instantly converted into high temperature high pressure steam to achieve a critical effect. The thermal-radiation internal-circulation power generation device is applied to large, middle and small power generation fields.

The invention discloses a heat storage method utilizing foam copper and ferromagnetic fluid. The heat storage method comprises the following steps that a magnetic field is provided to a heat storage main body through a magnetic field supply device, and the ferromagnetic fluid in the heat storage main body flows under the driving action of the magnetic field and a heat source of a heat source utilization device, and heat is stored; and a foam copper framework is further arranged inside the heat storage main body, and the foam copper framework and the ferromagnetic fluid are soaked with each other. Due to the fact that the heat conduction coefficient of the foam copper framework is high, the heat storage rate can be improved; due to the fact that the temperature-sensitive ferromagnetic fluidis sensitive to temperature, the convective heat transfer rate is high, the heat storage rate can be remarkably improved, and the temperature-sensitive ferromagnetic fluid has relatively high specific heat, so that the heat storage capacity can be improved.

A PCM system and method of shifting peak electrical load is provided with a PCM system including a heat exchanger, a storage tank coupled to the heat exchanger for storing PCM slurry, a pump coupled to the heat exchanger, an air conditioning unit coupled to the heat exchanger, and a heat rejection unit coupled to the storage tank. The PCM slurry is pumped from the storage tank to the heat exchanger. The energy at the heat exchanger is absorbed by the PCM slurry, and the PCM slurry is then returned to the storage tank. The energy absorbed by the PCM is rejected from the storage tank to a ground loop or by an air conditioning unit during a non-peak or less load demand period.

A method for producing phase change energy storage wax comprises the following steps: refining a Fischer-Tropsch synthetic wax raw material through hydrogenation reaction to obtain Fischer-Tropsch refined wax; primarily separating the Fischer-Tropsch refined wax to obtain a plurality of fractions; selecting a target fraction from the plurality of fractions to carry out sweating treatment to obtainphase change energy storage wax, wherein a sweating device adopted in the sweating treatment is provided with a tubular heat exchanger structure. According to the method, the raw material treatment process is simple, and the production cost is low. By adopting the improved sweating process, the solid-liquid separation efficiency can be improved, the separation effect is improved, and finally theproduct quality is improved.

A production process of nylon-6 coarse-denier high-strength yarns includes slicing, melting, metering, spinning, cooling, oiling, pre-interlacing, drafting and setting, main interlacing, and winding. In the slicing step, nylon-6 slices 2.8 to 3.2 in viscosity are selected. Melting is performed at the temperature of 270 DEG C to 280 DEG C. In the spinning step, pore diameter of a spinneret plate is 0.36mm, pore length is 1.08 mm, and initial pressure of a component is 135 bars to 142 bars. In the oiling step, oil resistant to high temperature, anti-static and high in cohesion is adopted. The nylon-6 slices of specific viscosity are used, the temperature of the melting step is adjusted, and a melt pipe, a spinning component, an oiling device, pre-interlacing and drafting and setting are modified, and the nylon-6 coarse-denier high-strength yarns up to 6.2Cn / dtex in breaking strength are produced.

The invention belongs to the fields of large-scale utilization of renewable energy sources as well as storage and transfer of heat energy, and discloses a high-heat-conductivity MgO doped molten nitrate heat-transfer and heat-storing material as well as an in-situ generation method and application thereof. The method comprises the following steps: mixing dried potassium nitrate and sodium nitrateaccording to the lowest eutectic point of a binary phase diagram to obtain a raw material mixture I of molten nitrate; adding magnesium chloride hexahydrate or magnesium nitrate hexahydrate into the mixture I according to the mass ratio of MgO to molten nitrate being (2.5-10.0):(97.5-90.0) to obtain a magnesium chloride hexahydrate or magnesium nitrate hexahydrate doped molten nitrate raw materialmixture II; after mixing the mixture II uniformly, heating to 420 to 500 DEG C through a program, and maintaining constant temperature for 10 to 24 hours to guarantee in-situ generation and crystallization of MgO to form MgO doped molten nitrate uniform fluid; and naturally cooling the fluid to room temperature to obtain the high-heat-conductivity MgO doped molten nitrate heat-transfer and heat-storing material.

The invention discloses a steam turbine oil composition and a preparation method thereof, and relates to the field of industrial lubricants. The steam turbine oil composition comprises the following components: (1) base oil; (2) an antioxidant; (3) an anticorrosive antioxidant; (4) an antirust agent; (5) an extreme pressure wear resisting composite agent; (6) an organic sulfonated substance or organic sulfonated polymer; (7) an anti-bubbling agent; (8) a demulsifying agent; (9) a dispersing agent. The preparation method of the steam turbine oil composition comprises the following steps: (1) weighing; (2) mixing compressed air; (3) mixing by using a mixing pump; (4) performing standing. The steam turbine oil composition provided by the invention is stable in quality, moderate in viscosity and good in liquidity, has excellent lubricating performance, extreme pressure wear resistance, cooling performance, high temperature stability and oxidation stability and relatively good bubbling resistance and demulsibility, and is very ideal steam turbine oil.

The invention relates to viscosity-controllable aqueous lubricating liquid and application. The viscosity-controllable aqueous lubricating liquid consists of triethanolamine borate, triethanolamine oleate, triethanolamine sebacic acid, an alcohol viscosifier, an organic silicon defoaming agent and water. The viscosity range is from 0.9 Pa.s to 8 Pa.s. The main component of the water-based lubricating liquid is water, so excellent characteristic, such as fire resistance, of the water and high specific heat are preserved; each component of the aqueous lubricating liquid has low price, no toxicity and high degradability and meets the requirements of environmentally-friendly lubricants; tests show that the aqueous lubricating liquid has high rust resistance; an anti-rusting agent component ofthe aqueous lubricating liquid comprises a polar group with a large adsorption force, so the aqueous lubricating liquid has anti-friction and anti-wear effects on a friction pair and prolongs the service life of equipment; and the viscosity of the lubricating liquid can be adjusted by changing the viscosifier content according to specific engineering requirements, so that the higher rigidity, bearing capacity and heat stability of a processing equipment main shaft and a hydrostatic guideway system are guaranteed.

The invention discloses an immersion-type heat radiation cooling liquid used for power lithium batteries, and a preparation method thereof, and belongs to the field of chemistry. The immersion-type heat radiation cooling liquid used for power lithium batteries is composed of, by weight, 30 to 70 parts of a hydrofluoroether compound, 30 to 50 parts of a halogenated hydrocarbon, 1 to 10 parts of analcohol compound, 0.01 to 0.5 part of an antioxidant, 0.01 to 0.5 part of a preservative, and 0.01 to 0.5 part of a nano metal oxide. According to the preparation method, the hydrofluoroether compoundis taken as a main component, and is mixed with the halogenated hydrocarbon, the alcohol compound, and the like to form an azeotrope, and the antioxidant, the preservative, and the non-conductive nano metal oxide additives are adopted as auxiliary additives to form the cooling liquid composition. The immersion-type heat radiation cooling liquid is excellent in heat radiation effect, is high in specific heat, low in expansion performance, low in toxicity, high in insulation performance, excellent in flame resistance, inert performance, and material compatibility, is capable of realizing heat transfer effect rapidly, is capable of solving power lithium battery heating and heat radiation problems effectively, prolonging battery service life, reducing failure risk, and improving battery safety performance.

A heat dissipating device includes a heat sink (10), a heat pipe (20), a heat reservoir (30) thermally connecting with the heat sink through the heat pipe, and a fan (40) generating an airflow through the heat sink. The heat pipe includes an evaporating portion (202) attached to the heat sink and a condensing portion (204) attached to the heat reservoir. The heat reservoir is made of metal containing working medium, such as water, therein. The heat reservoir stores or releases heat based on the amount of heat generated by the CPU to realize a compensation to the increase or decrease of temperature of the CPU, whereby the change rate of the temperature of the CPU from idle to busy condition and vice versa can be more stable.

The invention relates to heat-conduction fluid, which comprises the following components: 1.2-3.2 wt% of calcium chloride, 2.5-4.5wt% of absolute ethyl alcohol, 0.5-1.5wt% of sodium perborate, 1.2-2.7 wt% of sodium nitrate, 0.8-1.5wt% of potassium hydroxide, 1.2-2.7 of potassium phosphate, 0.2-0.8 wt% of benzotriazole and the rest of distilled water. The superconductive fluid disclosed by the invention has the characteristics of antifreezing property, antirust property, antifoam property, non-toxicity, environment-friendliness, stable property and good heat transmission effect. After a heat transmitter uses the heat-conduction fluid disclosed by the invention, the service life of the heat transmitter can be remarkably prolonged, and the heat transmission property of the heat transmitter can be remarkably improved.

The invention belongs to the technical field of physical heat transmission and energy storage in high and new technologies and relates to low-melting-point binary nitric acid mixed molten salt nanofluid. The low-melting-point binary nitric acid mixed molten salt nanofluid is made by compounding of a low-cost low-melting-point mixed molten salt and nano particles, the low-cost low-melting-point mixed molten salt is mainly composed of potassium nitrate and calcium nitrate, and types of the nano particles are one or two types of SiO2, Al2O3, TiO2 and MgO nanoparticles. The prepared novel low-melting-point binary nitric acid mixed molten salt nanofluid has a melting temperature of 127.4 DEG C, a decomposition temperature of 574.2 DEG C, a specific heat of about 1.73-1.91J / (g.K), a sensible heat storage cost of about 23.23yuan / (kW.h) and a heat conductivity coefficient of about 0.664W / (m.K). Compared with a low-melting-point binary mixed molten salt, the low-melting-point binary nitric acid mixed molten salt nanofluid has the advantage that the utilization temperature range is not changed sharply but specific heat is evidently increased by an increase ratio of about 17.8%.

The invention relates to an intelligent curtain wall daylighting roof. The intelligent curtain wall daylighting roof comprises a curtain wall board, wherein the curtain wall board is mounted in the outmost side of the top of a building; the curtain wall board is fixedly connected with a floor slab of the building through an outward inclined facade; a water insulation film is tightly adhered to the lower surface of the curtain wall board; a transparent, flexible and elastic dome is further mounted between the curtain wall board and the floor slab; the edge of the floor slab is fixed on the facade; the dome, the water insulation film and the facade form a lens layer at a liquid seal state; the lens layer is filled with transparent liquid; the lens layer is communicated with a liquid replacement layer in a closed way; a regulating device is mounted between the liquid replacement layer and closed space. The curtain wall daylighting roof can regulate the structure according to different seasons and climatic variation, and meanwhile has good light transmission and heat insulation effects.

The invention belongs to the technical field of spaceflight, relates to a thermal protection material for an outer layer of a space orbit spacecraft, and aims to improve thermal protective performance of the material and reduce the material density. The fundamental principle of the material is as follows: in a space microgravity environment, gas is very weak in natural convection and heat conduction and has good heat insulation performance. The thermal protection material is formed by a metal coating film with a bubble structure, the fundamental structure is that a certain bubble structure is distributed on the surface of the metal coating film, and a certain type of gas with certain pressure is sealed in bubbles, which are shown in attached pictures. The spaceflight thermal protection material has the advantages of low density, high specific heat and good thermal protective performance.

The invention relates to a heat-transfer medium specially used for a solar energy heat pump, which comprises the following components: 0.15-0.65wt% of calcium chloride, 0.5-1.75wt% of absolute ethyl alcohol, 0.5-1.2wt% of sodium perborate, 0.3-0.8wt% of sodium nitrate, 0.2-0.75wt% of sodium benzoate, 0.3-0.8wt% of potassium borate, 0.2-1.2wt% of benzotriazole and the balance of distilled water. The heat-transfer medium specially used for the solar energy heat pump provided by the invention is characterized by freezing resistance, rust resistance, foam-proof property, non-toxic, environment-friendly property, stable performance and excellent heat-transfer effect.

A method for preparing the shaped sleeve includes such steps as sleeving the blank on a shaping mould, putting it in water tank, heating the water, and making water temp constant for a certain time. Its advantages are high heat conducting speed, less loss of heat and high thermal uniformity.

The invention provides a spatial efficient heat transfer micropump-driven fluid loop, made by welding and integrating an integrated mounting board, a micropump controller, two micropumps, a first heat sink, a second heat sink, a liquid storage device, two one-way valves, stainless steel pipes and supporting tees; the two micropumps and the two one-way valves are two independently parallel paths, backup for each other; the two micropumps are connected to the first heat sink, the second heat sink, the two one-way valve and the liquid storage device respectively through the stainless steel pipes and the supporting tees, and the two one-way valves are mounted respectively between the two micropumps and the first heat sink and liquid filling valve; one end of the liquid storage device is connected to an inflating valve though a stainless steel pipe, the inflating valve and the liquid filling valve are connected to the stainless steel pipe respectively through ferrules, the micropump controller is connected with the two micropumps, and the micropump controller controls a thermal switch and controls heat transfer by controlling start-stop and speed of the micropumps. Heat is quickly transferred between the heat sinks through micropump-driven medium water, the function of quickly balancing temperature differences is provided, and high adaptability to changes in extra-rail heat flow and inner power consumption is provided.

The invention discloses a low-melting-point nano molten salt heat transfer and storage medium and a preparation method and belongs to the technical field of physical heat transfer and energy storage in advanced technologies. The low-melting-point nano molten salt heat transfer and storage medium is prepared from low-melting-point mixed molten salt and nanoparticles in a composite mode. The low-melting-point mixed molten salt is mainly composed of potassium nitrate, sodium nitrate, calcium nitrate and lithium nitrate. The nanoparticles are nanoparticles of metallic oxide or nonmetallic oxide. According to the novel low-melting-point nano molten salt prepared through the method, the melting point is 80-130 DEG C, the decomposition temperature is approximately 600 DEG C, and compared with the low-melting-point mixed molten salt, the using temperature range of the low-melting-point nano molten salt does not change greatly, but the specific heat is improved remarkably by about 10-60%.

The invention provides a transformer heat dissipation apparatus and a heat dissipation intelligent control system using the transformer heat dissipation apparatus. The transformer heat dissipation apparatus comprises a case for accommodating a transformer and a heat dissipation device, the heat dissipation device is installed on the case, the case is provided with a case shell, and the case shellis filled with a condensate a with high specific heat; a plurality of through holes are formed in the upper portion of the case shell and evenly formed in the upper portion of the case shell; and theheat dissipation device is vertically embedded in the through holes. The heat dissipation intelligent control system of the transformer heat dissipation apparatus comprises a temperature detection device, a temperature monitoring device, an execution mechanism and an alarm device, the temperature detection device is used for detecting the temperature of the condensate, the temperature monitoring device is used for comparing the temperature of the condensate with a preset temperature, and the execution mechanism is used for controlling the opening degree of a valve of an atomization pipeline inan atomization device; and the alarm device is used for giving an alarm when the temperature T1 of the condensate a or the temperature T3 of a condensate c exceeds the early warning temperature T4 ofthe condensate a or the condensate c.

The invention relates to an intelligent curtain wall daylighting roof. The intelligent curtain wall daylighting roof comprises a curtain wall board, wherein the curtain wall board is mounted in the outmost side of the top of a building; the curtain wall board is fixedly connected with a floor slab of the building through an outward inclined facade; a water insulation film is tightly adhered to the lower surface of the curtain wall board; a transparent, flexible and elastic dome is further mounted between the curtain wall board and the floor slab; the edge of the floor slab is fixed on the facade; the dome, the water insulation film and the facade form a lens layer at a liquid seal state; the lens layer is filled with transparent liquid; the lens layer is communicated with a liquid replacement layer in a closed way; a regulating device is mounted between the liquid replacement layer and closed space. The curtain wall daylighting roof can regulate the structure according to different seasons and climatic variation, and meanwhile has good light transmission and heat insulation effects.

The invention relates to a preparation method of a B4C modified C / C-SiC brake material. According to the method, a vacuum pressure dipping method is used for introducing a B4C powder material in a three-dimensional needle carbon felt with the initial density being 0.4 to 0.6g / cm<3>; CVI (chemical vapor infiltration) and RMI (reaction melt infiltration) are combined for preparing the C / C-SiC brake material. When the B4C modified C / C-SiC brake material is used, on one hand, the B4C is used as a self heeling component for achieving the protection effects on the carbon fiber and a carbon base body; the inoxidizability of the material can be obviously improved; on the other hand, the B4C has higher specific heat capacity; the integral specific heat capacity of the material can be improved; the braking temperature can be effectively reduced; the material friction performance stability is improved.

The invention provides an energy-saving and quick-acting intelligent household superconducting liquid heating radiator, which comprises an upper circulation pipe, a lower circulation pipe, a heat dissipation pipe, a superconducting liquid, a power switch, a control system, a heating rod and a base, and the heat dissipation pipe includes Outer tube and inner tube; Described control system comprises flow sensor and warning system; Described warning system comprises warning light; Described flow sensor controls the flow rate of the superconducting liquid in described radiating pipe lumen; When the liquid leaks, the warning system starts, the warning light turns red, and the control system automatically cuts off the power supply to prevent danger from happening. The radiator of the present invention has the advantages of simple structure, energy saving and high efficiency, low cost, no liquid leakage, intelligent liquid leakage warning, superconducting liquid through a reasonable component distribution ratio, superconducting liquid is safe and non-toxic, high specific heat, good thermal conductivity, and low-temperature fluidity it is good.

The invention provides a computer coolant. The computer coolant is prepared from the following components in percentage by weight: 1000-2000 parts of N-methyl pyrrolidone, 200-400 parts of glycol, 0.5-5 parts of a silane coupling agent, 0.5-5 parts of silicone, 0.5-2 parts of 1-hexyl-2,3-dimethylimidazolium hexafluorophosphate, 0.5-2 parts of N-butylpyridinium hexafluorophosphate, 0.1-0.5 part ofcopper powder, 0.1-0.5 part of graphite powder, and 0.1-0.5 part of a defoamer. The computer coolant has the steam pressure close to zero, thus is not liable to volatilize, meanwhile has high thermalconductivity, the high specific heat, the low solidification point, the low viscosity and the high flash point and has good compatibility with materials such as fluid pipelines of cooling systems andmetals and rubber of accessories, and the coolant is also environmentally friendly and good in environmental protection. The computer coolant can be applied as the computer coolant and can also be applied as an engine coolant.

The invention relates to a method for improving a carbonized wood property by silica sol impregnation pretreatment. The method comprises the following steps of: placing wood in a treatment tank, carrying out the silica sol infusion pretreatment on the wood, and carrying out stacking and air dry on the treated wood; carrying out common kiln drying on the treated wood so as to enable the water content ratio of the wood to be reduced to be 12-18%, and then discharging the dried wood out of a kiln, placing the wood after drying in charring equipment for carrying out hot modification carbonizing treatment; and finally taking out the wood. The method provided by the invention has the advantages that silica sol is adopted to be used as modification liquid so as to carry out the impregnation pretreatment on the wood, the front drying is not needed, the manufacturing cost is low, the mass loss rate of preparative carbonized wood is reduced, and the equilibrium water content is reduced; and the dimensional stability. the density and the mechanical strength are improved, corrosion proof and weather resisting properties are improved, flame retardant and termite proof properties can be improved to a certain degree, and the method has the characteristics of being odorless, innoxious, safe and environment-friendly.