The objectives of this study are to compare the energy consumption rate (ECR) of battery electric bus (BEB) simulated from international driving cycles and a real-world driving cycle in Chiang Mai ...(CMDC) and to define the ECR multiplier to convert the simulated ECR obtained from international driving cycles to the CMDC. Four international driving cycles were chosen. Each driving cycle was separately considered for two cases, one with air resistance and one without. It was concluded that the ECR obtained from the EPA heavy duty urban dynamometer driving schedule (EPA HDUDDS) is most similar to the CMDC but the ECR obtained from the regulation of the worldwide harmonized light vehicles test procedure (WLTP) differs the most. The ECR multipliers used for correcting the simulated ECR were in a range between 0.839 and 1.711.
The condensed working fluid inside a heat pipe is pumped from the condenser to the evaporator section to complete the operating cycle by using the capillary force generated inside the wick structure. ...Since the miniature heat pipes have smaller vapor cross-sectional area, the fiber wick structure is suitable for this application. The fiber wick structure can be designed to provide an excellent flow path for the working fluid with an optimum configuration based on a hexagonal fiber arrangement. By a microscopic investigation of the wick structure, the porosity can be related with the physical properties, effective pore radius and the capillary pressure. The effective pore radius and the capillary pressure are important parameters to characterize the permeability because it enables one to predict the flow rate obtainable under a given pressure drop necessary to achieve a specific circulation condition, which affects the heat transfer for the heat pipes. In this study, the effect of the porosity on the effective pore radius and the capillary pressure are discussed. The rate of the test liquid rise has been used to estimate the permeability on several fiber wick samples where the porosity varies. The optimum porosity of the fiber wick structure in miniature heat pipes is found at 0.45 while the permeability approaches the maximum value of 1.26 × 10
−12
m
2
which results in an excellent circulation of the working fluid from the condenser to the evaporator section. Moreover, the capillary performance (
K
/
r
eff
) of the fiber wick is further investigated for the thermal evaluation of heat pipes. The values of the maximum heat transfer rate due to capillary limit from our prediction reach to 1.81 and 2.68 W for heat pipe diameters of 2 and 3 mm, which contain sintered fiber wick structures under optimum design conditions.
This research aims to design an optimal closed-loop pulsating heat pipe (CLPHP), which is applied as a heat transfer device to replace the thermosyphon in a commercial evacuated tube solar water ...heater system (ETSWH). It is evaluated by high thermal performance and maximum net saving as described by the Net Saving Method and economic analysis. The CLPHP samples were designed by varying the parameters such as 1.50 and 1.78 mm inner diameter, 1.00, 1.25 and 1.50 m evaporator length with 1, 2 and 4 sets of the CLPHP (20 turns per set). The adiabatic and condenser sections were 0.05 and 0.3 m in length, respectively. An ETSWH with various samples of CLPHP was tested using a solar simulator (Indoor) that followed the EN 12975-2 standard. The components of the optimal system consisted of 10 evacuated tubes. The water capacity was 100 L. The experimental results indicated that the optimal CLPHP consisted of 1.50 mm inner diameter, 1.25 m evaporator length and 4 sets. The overall heat rate of water obtained was 518 W, with a net saving of 901.4 USD over 10 years and an investment of 482.4 USD with a simple payback period of 3.3 years.
This experimental study aims to emphasize on thermal performance and temperature variation of the closed-loop pulsating heat pipe (CLPHP) affected by various adiabatic section lengths. A capillary ...copper tube has been bent to have 10 and 20 meandering turns to form the CLPHPs with 1.78 mm internal diameter. The evaporator section length was 150 mm, which was the same as of the condenser section length. The adiabatic section length was varied from 75 to 150, 300, and 450 mm. Ethanol, R123, and water was selected to be working fluid with the volumetric filling ratio of 50%. Hot water was pumped through the heating jacket for supplying the heat input to the evaporator section. Heat flux selected as the thermal performance in this study was measured by means of the calorific method across the cooling jacket enveloping the condenser section. It could be concluded that effect of the adiabatic section length has two different trends that are: (i) When the adiabatic section length increases, the heat flux continuously increases until the evaporator section length exceeds a certain value, the heat flux then decreases. And (ii) when the adiabatic section length increases, the heat flux continuously increases. The different effects between both trends are depended on the working fluid’s flow velocity, surface tension, density, and viscosity.
The fuel and energy consumptions between different drive modes of the diesel hybrid electric bus were simulated and compared in this study. The simulated consumptions from two different hybrid modes ...were compared to the one obtained from the pure diesel mode and the pure electric mode. The backward simulation scheme was used to determine the required traction power of vehicles at specified vehicle velocity and time entire the driving cycle defined in the EPA heavy duty urban dynamometer driving schedule. The summation of fuel consumption of diesel engine, which was referred to the theoretical model of the diesel cycle, and the electric energy consumption of the motor were set as the total energy consumption at a certain specified time of the diesel hybrid electric bus. The conclusion showed that the combination of the drive mode with higher percentage of motorized power can reduce the summation of energy consumption and the energy cost of the diesel hybrid electric bus.
This research was aim to investigate the thermal characteristics of the rotating closed-loop pulsating heat pipe (RCLPHP) designed for integrating onto rotating-type energy storage devices. The ...thermal characteristics beginning from the start-up state to the post-critical state were thoroughly observed. The RCLPHP was made from 1.78-mm inner diameter copper tube and it was bent to be 11 meandering turns. The evaporator section length was 50 mm, which was the same as of the condenser section. Working fluid was distilled water. Filling ratio was 50% of total volume. It was installed on a rig and oriented in vertical plane. Annular plate electrical heaters were used to supply heat input. The heat released from the condenser section to the ambient air at constant temperature of 25 ± 1 °C. The rotational speed was 70 rpm. It could be found that when the RCLPHP worked in the normal operating state, the evaporator and the condenser section temperatures fluctuated with obvious frequency and amplitude, and the internal phenomena of the working fluid could be implied as the slug-train. When the RCLPHP has reached the critical state, the condenser section temperature subsequently decreased. This is because the condensate is strongly pushed by the centrifugal force against the vapor flow direction, then the vapor plugs cannot flow to transfer the heat to the condenser section as usual.
The objective of this study was to determine the suitable specific energy consumption (SEC) of cold storage rooms for chilled (0–10 °C) and frozen (≤-18 °C) cold stores in Thailand. A survey of ...refrigerated warehouses in Thailand was conducted to determine the energy consumption under actual operating conditions. The survey included 161 cold storage rooms (48 chilled cold stores and 113 frozen cold stores) over a range of store volumes between 20 and 108,220 m3. The parameters used for the analysis were temperature of the store, volume of the store and energy usage per year. The SEC was determined from the relationship between the annual energy consumption and store volume following European Standard EN 16212:2012. It was found that the SEC decreased with increasing volume of the warehouse in a power function form. They varied between 37 and 481 kWh/m3-year for chilled cold stores, and between 46 and 212 kWh/m3-year for frozen cold stores. According to the regression equation, the suitable SECs for each cold store type in Thailand were 1,630.3 × (store volume)−0.3812 and 1,560.0 × (store volume)−0.2917 kWh/m3-year for chilled and frozen cold stores, respectively. The equation form was consistent with results from other studies.
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