The strive towards ever increasing automotive engine efficiencies for both diesel and gasoline engines has in recent years been forced by ever-stringent emissions regulations, as well as the introduction of fuel consumption regulations. The untapped availability of waste heat in the internal combustion engine (ICE) exhaust and coolant systems has become a very attractive focus of research attention by industry and academia alike. Even state of the art diesel engines operating at their optimum lose approximately 50% of their fuel energy in the form of heat. As a result, waste heat recovery (WHR) systems have gained popularity as they can deliver a reduction in fuel consumption and associated CO2 emissions. Of these, the Organic Rankine Cycle (ORC) is a well matured waste heat recovery technology that can be applied in vehicle powertrains, mainly due to the low additional exhaust backpressure on the engine and the potential opportunity to utilize various engine waste heat sources. ORCs have attracted high interest again recently but without commercial exploitation as of today due to the significant on-cost they represent to the engine and vehicle. In ORCs, expansion machines are the interface where useable power production takes place; therefore, selection of the expander technology is directly related to the thermal efficiency of the system. Moreover, the cost of the expander-generator units accounts for the largest proportion of the total cost. Therefore, selection of the most appropriate expander is of great importance at the early stage of any automotive powertrain project. This study aims to review the relevant research studies for expansion machines in ORC-ICE applications, analyzing the effects of specific speed on expander selection, exploring the operational characteristics of each expander to further assist in the selection of the most appropriate expander, and comparing the costs of various expanders based on publically available data and correlations.

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Expander Technologies for Automotive Engine Organic Rankine Cycle Applications

Performance evaluation of energy efficient evaporatively air-cooled chiller

Evaporative condensers are regarded as highly-efficient and eco-friendly heat exchangers in refrigeration systems. Data-driven methods can play a key role in performance prediction of evaporative condensers, conducted without the complexity of theoretical analysis. In this study, four machine learning models including multi-layer perceptron artificial neural network (ANNMLP), support vector regression (SVR), decision tree (DT), and random forest (RF) models have been employed to predict heat transfer rate and overall heat transfer coefficient of a small-scale evaporative condenser functioning under a wide range of working conditions. A set of experimental tests were conducted, where inlet air dry/wet-bulb temperatures, spraying water and condenser saturation temperatures, refrigerant, and air flow rates were considered as main influencing parameters. The results show that the ANNMLP followed by SVR, and RF models possess the best generalization capability. Further, the dataset size analysis indicates that SVR is the best model to predict heat transfer rate for small dataset sizes. Additionally, feature importance analysis by the RF model reveals that refrigerant flow rate is the most influencing parameter.

A comparative study of various machine learning methods for performance prediction of an evaporative condenser

Heat conductive plastic heat exchange module used for countercurrent closed cooling tower

The invention relates to a device and a method for measuring a drifting rate of a cooling tower. A supporting foot fixed member is fixedly connected with a hexagonal bracket supporting foot, and six hexagonal bracket supporting feet are respectively fixedly connected with high-efficient water receiving devices which respectively have the models A to F through water receiving device fixed members. The selection of each high-efficient water receiving device is determined by the diameter of an air duct, and each high-efficient water receiving device is respectively connected with a scale pipe through a guide pipe; or two supporting rods are fixedly connected to a square air port through a supporting rod fixed member, the lower ends of the two supporting rods are respectively fixedly connected with an M-model high-efficient water receiving device and an N-model high-efficient water receiving device respectively through water-receiving device fixed members, and the M-model and the N-model high-efficient water receiving devices are respectively connected with the scale pipe through the guide pipes. The drifted water at an outlet of the cooling tower within a water receiving area can be completely collected without being influenced by approximately-saturated wet hot air, and more accuracy is realized; and the process for repeatedly utilizing a high-precision scale to weigh can be canceled, and more simplicity and convenience can be realized.

Device and method for measuring drifting rate of cooling tower

Nominal condensing capacity and performance evaluation of evaporative condenser

The utility model relates to a device for measuring the drifting rate of a cooling tower. Hexagonal bracket support legs are fixedly connected to a circular air outlet through support leg fixing members, and type A-F high-efficiency water collectors are fixedly connected to the six hexagonal bracket support legs through water collector fixing members. Each high-efficiency water collected is selected according to the diameter of a blower and is respectively connected with a scale pipe trough a guide pipe; or two support rods are fixedly connected to a square air outlet through support rod fixing members, a type-M high-efficiency water collector and a type-N high-efficiency water collector are fixedly connected to the lower sides of the two support rods through water collector fixing members, and the type M high-efficiency water collector and the type-N high-efficiency water collector are respectively connected with a scale pipe through a guide pipe. The device disclosed by the utility model has the capability of nearly completely collecting drifting water at the outlet of the cooling tower in a water collection area and is free from the influence of almost saturated damp and hot air, thereby being more accurate; and the device disclosed by the utility model is simpler and more convenient because a process of weighting by repeatedly using a high-precision balance is saved.

Device for measuring drifting rate of cooling tower

The utility model relates to a heat-conducting plastic heat transfer module for a counter-flow closed cooling tower. The heat transfer module comprises upper collecting pipes, lower collecting pipes and a module frame. The upper collecting pipes and the lower collecting pipes are fixed on the module frame respectively. Two ends of a plurality of heat-conducting plastic thin pipes are subjected to hot melting onto the upper collecting pipes and the lower collecting pipes respectively to form a layer of heat-conducting plastic thin pipe grids. Partition plate bars are arranged among the thin pipes to keep space, and the middles of the thin pipe grids are fixedly connected onto fixing plates on two sides through support rods respectively. Tension units are arranged between the fixing plates and the module frame respectively, and used for balancing heat-conducting plastic thin pipe own deformation along length direction of the pipes caused by temperature differences and pulling. According to the heat-conducting plastic heat transfer module for the counter-flow closed cooling tower, a large heat-transfer area can be provided in limited space; the freezing resistance and the corrosion resistance are excellent; the tension units can enable the thin pipes to keep straight, reduce circulation resistance in pipes and improve the water spraying evenness. Thermal performances of a closed tower provided with the module can be improved, and application ranges can be expanded. Further, the manufacture cost of the heat-conducting plastic pipes is far lower than that of metal pipes, so that the manufacture cost of the closed tower utilizing the heat-conducting plastic heat transfer modules can be reduced.

Ye Jun

Papers

Nominal condensing capacity and performance evaluation of evaporative condenser

Heat conductive plastic heat exchange module used for countercurrent closed cooling tower

Device for measuring drifting rate of cooling tower

Heat-conducting plastic heat transfer module for counter-flow closed cooling tower