汽车发动机水冷系工艺特点

随着汽车的普及,汽车已走进寻常百姓家,掌握冷却系主要部件散热器、节温器、水泵等的检查、维护与调整的方法,冷却系的作用是吸收和散发掉发动机的多余热量,以保证发动机在适宜温度下工作。

发动机水冷系故障分析

发动机在工作过程中,冷却系常见的故障直接外在表现不外乎水温过高或过低。水温过低的原因相对来说比较容易判断。其主要原因是节温器工作失常,循环水长时间处于大循环状态,导致发动机过分冷却。另外在寒冷的冬季不正确使用保温装置也是原因之一。 发动机水温过高,可分为两种原因:一、冷却系统故障。二、人工操作调整因素。

Performance analysis on a novel water chiller using liquid desiccant

A new type of liquid desiccant water chiller for applications on air-conditioning and refrigeration is introduced.The system can be driven by low-grade heat sources with temperatures of 60 to 80 ℃,which can be easily obtained by a flat plat solar collector,waste heat,etc.A numerical model is developed to study the system performance.The effects of different parameters on performance are discussed,including evaporating temperature,regenerating temperature,ambient condition,and mass flow rates of closed moist air and regenerating air.The results show that an acceptable performance of a cooling capacity of 2.5 kW and a coefficient of performance of 0.37 can be achieved in a reference case.The regenerating temperature and the humidity ratios of ambient air are two main factors affecting system performance,while the temperature of ambient air functions less.In addition,the mass flow rate of regenerating air and closed moist air should be carefully determined for economical operation.

Application of water loop variable refrigerant flow air-conditioning system in large-scale buildings in northern China

A water loop variable refrigerant flow（WLVRF）air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a variable refrigerant flow（VRF）air-conditioning unit,a water loop and an air source heat pump.The water loop transports energy among different regions in the buildings instead of refrigerant pipes,decreasing the scale of the VRF air-conditioning unit and improving the performance.Previous models for refrigerants and building loads are cited in this investigation.Mathematical models of major equipment and other elements of the system are established using the lumped parameter method based on the DATAFIT software and the MATLAB software.The performance of the WLVRF system is simulated.The initial investments and the running costs are calculated based on the results of market research.Finally,a contrast is carried out between the WLVRF system and the traditional VRF system.The results show that the WLVRF system has a better working condition and lower running costs than the traditional VRF system.

Synthesis and application of an environmentally friendly antiscalant in industrial cooling systems

Allylpolyethoxy carboxylate macromonomers possessing polyethylene oxygen long chains were synthesized by advanced technology of the polyether cap.A novel double-hydrophilic block copolymer was prepared through free radical polymeric reactions in aqueous solution and its performance on CaCO3 inhibition and dispersancy activity towards Fe2 O3 was evaluated in recirculating cooling water systems.The study shows that acrylic acid-allylpolyethoxy carboxylate has a significant ability to inhibit the precipitation of calcium carbonate and an excellent dispersing capability to stabilize iron Ⅲ in industrial cooling systems. X-ray diffraction shows that there is a number of vaterite crystals in the presence of the phosphorous free and non-nitrogen copolymer. The change in crystal forms is also confirmed by the Fourier-transform infrared spectra the scanning electron microscopy and the transmission electron microscopy. The inhibition mechanism is proposed and it shows that the interactions between calcium and polyethylene glycol PEG are the fundamental impetus for restraining the formation of the scale in cooling water systems.

Design of Heat Pipe Type Adsorption Ice Maker for Fishing Boats

A heat pipe type adsorption ice maker with two adsorbers for fishing boats is designed by using ammonia as refrigerant and compound of activated carbon-CaCl2 as adsorbent. This type of heat pipe adsorber can solve the problem of incompatibility between ammonia, copper, seawater and steel. The working process of the ice maker with 8.7kg adsorbent per bed is simulated. The results show that the optimal semi-cycle time is about 9 min at the evaporating temperature of -15℃, where the corresponding cooling power, specific cooling power per kilogram adsorbent SCP and coefficient of refrigerant performance COP are respectively 3.6kW, 217W·kg-1 and 0.404.

Effects of Nutrients on Biofouling Formation and Preponderant Bacteria Diversity in Recirculating Cooling Water System

A series of orthogonal array experiments were conducted using carbon source, ammonia nitrogen and total phosphorus （TP） as major influencing factors to investigate the effects of nutrients on biofouling formation and preponderant bacteria diversity in the recirculatiug cooling water system. Carbon source was demonstrated to be the most significant determinant affecting the biofouling formation. A minimum biofouling outcome was obtained when BOD2, NHa＋-N and TP were 25, 10, and 1 mg/L, respectively. Then the preponderant bacteria strains in biofouling mass under two typical culture conditions （negative and favorable） were identified applying both traditional biochemical methods and further molecular biology technology with phylogenetic affiliation analysis, which indicated that Enterobacteriaceae Enterobacter, Micrococcaceae Staphylococcus, Bacillaceae Bacillus, Enterobacteriaceae Proteus, Neisseriaceae Neisseria and Pseudomonadaceae Pseudomonas were dominant under negative condition, while Enterobacteriaceae Klebsiella, Enterobacteriaceae Enterobacter and Microbacterium - under favorable one.

Laccase Immobilized on Mesoporous Silica Materials and Its Corrosion Inhibition Performance in Circulating Cooling Water System

Mesoporous SiO_2 microspheres were synthesized using the sol-gel method and were characterized by TEM, FT-IR and BET techniques. The diameter of the microspheres is about 100—150 nm, and the average mesopore diameter is 2.55 nm, while the specific surface area is 1 088.9 m2/g. Mesoporous SiO_2 microspheres adsorb glutaraldehyde and immobilize laccase by means of the aldehyde group in glutaral which can react with the amidogen of laccase. The immobilization conditions were optimized at a glutaraldehyde concentration of 0.75%, a crosslinking time of 8 h, a laccase concentration of 0.04 L/L and an immobilization time of 10 h. When diesel leakage concentration was 80 mg/L, the highest corrosion inhibition efficiency of immobilized laccase reached 49.23%, which was slightly lower than the corrosion inhibition efficiency of free laccase(59%). The diesel degradation ratio could reach up to 45%. It has been proved that the immobilized laccase could degrade diesel to inhibit corrosion.

Optimum Scheduling for the Chilled Water System of an Intelligent Building

The energy saving issue of chilled water system in an intelligent building is analyzed from the systematic point of view, and an optimum scheduling scheme which can save energy of the system facilities and satisfy the constraints of the real time cold loads and system running is also proposed. It can make the minimum cost of the system by optimizing the number of running chillers, running parameters and the distribution of real time loads of running chillers. The improved genetic algorithm is used in the optimum scheduling scheme. The computation results show that the building energy consumption can be decreased by about 10%.

Simulation of Gas-Fired Triple-Effect LiBr/Water Absorption Cooling System with Exhaust Heat Recovery Generator

An exhaust heat recovery generator is proposed to be integrated with conventional gas-fired triple-effect LiBr/water absorption cooling cycles to improve system energy efficiency. As a case study, simulation of the novel cycle based on promising parallel flow with cooling capacity of 1 150 kW is carried out under various heat recovery generator vapor production ratios ranging from 0 to 3.5%. The life cycle saving economic analysis, for which the annual gas conservation is estimated with Bin method, is employed to prove the worthiness of extra expenditure. Results show that the optimum gas saving revenue is obtained at 2.8% heat recovery generator vapor production ratio with 42 kW exhaust heat recovered, and the system energy efficiency is improved from 1.78 to 1.83. The initial investment of exchanger can be paid back within 7 years and 9 000 CNY of gas saving revenue will be achieved over the 15-year life cycle of the machine. This technology can be easily implemented and present desirable economic effects, which is feasible to the development of triple-effect absorption cycles.

Influence of Cooling Systems on the Behaviour of Dairy Cows Housed in Cubicle Barn

The aim of this paper is to collect information about dairy cow＇s behaviour connected to different environmental conditions. During summer 2009 and winter 2010 experimental trials were arranged to verify the behaviour of dairy cows in a farm located in Po Plain （Italy）. The barn was provided with an air-water cooling system, based on the use of fans and sprinklers placed only in the feeding alley. Two different trials were carried out. The first experiment was targeted on verifying the use of the cubicles by the cows in relation to the availability of the cooling system only in feeding area. The second trial aimed at testing the effectiveness of zone cooling systems placed in the front of cubicles. For this purpose three cubicles in the barn were provided with cooling systems, based on the input of high velocity conditioned air streams. The results clearly remark that the behaviour of the animals is greatly influenced by the environmental conditions. With high temperatures the use of the cubicles is deeply reduced and the animals prefer to stay in feeding area, thus benefiting from the cooling effect of water sprinkled by the showers and of the air streams created by the fans. With air temperatures increasing from 21℃ to 33 ℃ the cows reduce the staying in the cubicles, which gets down from 540 to 32% （r2 = 0.2608）. As regards the efficacy of zone cooling system in the cubicles, the results are not particularly encouraging. The cows continue to use the cubicles without changing the behaviour in relation to the presence of conditioned air flow.

Adsorption Refrigeration Performance of Shaped MIL-101-Water Working Pair

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa （MIL-101-3）. The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.

Integrated utilization of low-grade thermal energy in hot coal mine

This paper explores the integrated utilization of low-grade thermal energy in hot coal mines, based on analysis of original heating, refrigerating, mine draining, bath draining and air exhaust systems, and in combination with the actual conditions of Tangkou Coal Mine in Shandong Province. It presents a set of comprehensive and integrated utilization schemes for the various different kinds of low quality heat energy. With heat pumps, the recycling of the low quality heat energy from the drainage, bathing water and the exhaust air can occur in winter, and in summer, there exists condensed heat of the refrigerating system. When in conjunction with solar collectors, the thermal utilization of solar power can be realized for the whole year. The system achieves mine drainage and bathing water purification and recycling, as well as purifying exhaust air by water spraying. It also satisfies the demands of a whole year＇s bathing heat for the coal mine, with refrigeration in summer, and heating for the ground house and shaft house in winter. It is able to integrate different kinds of low quality heat energy and low emission drainage and dust, and can replace the traditional boiler heating system. Finally, the system reduces conventional energy consumption and the amount of mine water drainage.

Experimental Performance of Moderate and High Temperature Heat Pump Charged with Refrigerant Mixture BY-3

Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.

Energy performance assessment on central air-conditioning system of commercial building: A case study in China

Energy performance assessment on central air-conditioning system is essential to optimize operating, reduce operating costs, improve indoor environmental quality, and determine whether the retrofitting of the equipment is necessary. But it is difficult to evaluate it reasonably and comprehensively due to its complexity. A "holistic" approach was discussed to evaluate the energy performance of central air-conditioning system for an extra-large commercial building in a subtropical city. All procedures were described in detail, including field investigation method, field measurement instruments, data processing and data analyzing. The main factors affecting energy consumption of air-conditioning system were analyzed and the annual cooling-energy use intensity of this building was calculated and also compared with other shopping malls and other types of buildings in Guangzhou. And COP(coefficient of performance) of chiller, water transfer factor of chilled water system and cooling water system were taken into consideration. At last, the thermal comfort and indoor air quality issues were addressed. The results show that the chilled water pumps are over-sized and the indoor environmental quality should be improved. The purpose of this work is to provide reference for energy performance assessment method for air-conditioning system.

OECD/NEA ROSA Project Experiment on Steam Condensation in PWR Horizontal Legs during Large-Break LOCA

Separate-effect experiment simulating steam direct-contact condensation on ECCS （emergency core cooling system） water in PWR （pressurized water reactor） cold legs during reflood phase of large-break LOCA （loss-of-coolant accident） was conducted in OECD/NEA ROSA Project using the LSTF （large scale test facility）. A new test section was furnished in the downstream of the LSTF break unit horizontally attached to the cold leg. Significant condensation of steam appeared in a short distance from the simulated ECCS injection point, and the steam temperature in the test section decreased immediately after the initiation of the ECCS water injection. Total steam condensation rate estimated from the difference between steam flow rates at the test section inlet and outlet was in proportion to the simulated ECCS water mass flux until the complete condensation of steam. Clear images of high-speed video camera were successfully obtained on droplet behaviors through the viewer of the test section, especially for annular mist flow.

Treatment of Dairy Wastewater Effluent Using Submerged Membrane Microfiltration System

Dairy wastewater effluent has become one of the major concerns for the dairy processing industries. Because of large of wastewater effluent generation, the dairy processing industries may become potential candidates for wastewater reuse. Treated wastewater can be utilized in cooling systems and washing plant floor, as well as its potential use for greenery irrigation purposes. In addition, treating dairy effluent will also benefit the environment. The purpose of this study is to characterize wastewater from a selected dairy industry in Kuwait （Kuwait Dairy Company） and a study of applying micro filtration treatment process for treating the dairy wastewater. A complete treatment system including biological treatment, powdered activated carbon （PAC） and submerged membrane microfiltration system （CMF-S） was installed at Kuwait Institute for Scientific Research （KISR） research plant. The overall results of this study indicate that the complete system is capable of treating the dairy effluent. The average removal efficiencies of the system for biological oxygen demand （BOD）, chemical oxygen demand （COD）, total dissolved solid （TDS） were 98.8%, 92.5%, 96.7% respectively.

Using Condensed Water of Air Conditioners for Toilet Flushing： A Case Study in Brazil

Within the concept of sustainable construction, with sensible and conscious use of finite natural resources, every effort to save and reuse raw-materials is considered an important step to be adopted in buildings, from project, implantation and construction to operation and maintenance throughout their lifecycle. This study aims at showing the application of a system that reuses condensed water drained from air-conditioner evaporators （which are usually disposed of）, and a plan to use this water for toilet flushing, reducing consumption of treated water bought from water companies. The authors verified that each air-conditioner specified in the project of a commercial building--used as reference here--produces 4.8 L of water per hour of operation. This result in a daily accumulated volume of 4,290 L, which represents a significant part of the amount needed to supply all the toilets in the building. A water capture system located at a strategic intermediate floor would be able to store this water and pump it into a special reservoir on the roof of the building, to be distributed into toilet flush pipes. By applying this technology, the authors seek to considerably reduce the expected treated water consumption and consequently decrease water bill costs.

The Comparison between Solar Water Distillation with and without a Cooling Tube

A solar still system is designed and built to utilize solar energy in the Gulf States region to produce fresh water from brackish and sea water. This experimental work has been conducted with and without a cooling tube. The results showed that the daily production rate of the simple solar still without a cooling tube is slightly higher than that with a cooling tube. This could be due to the fact that the cooling tube has a smaller effective condensation surface area than the glass cover of the simple still. The cooling tube also reduces the solar energy that reaches the water in the still. It might also be due to the fact that the use of a cooling tube has the effect of reducing the average temperature in the solar still cavity. This resulted in reducing the evaporation rate and consequently reduced the production rate.