Optimization and Operational Analysis of Electric Vehicle Operation with Fast-Charging Technologies

This work presents three demos, which include Electric Buses (EBs) from four various brands with lengths of 12 m and 18 m and an Electric Truck (E-truck) for refuse collection. The technical operation of these EVs were analyzed to implement further operational cost optimization on the demo vehicles. The Electric Vehicles (EVs) were tested against superfast-charging solutions based on Pantograph (Type A & Type B) on the route lines (and depots) and based on Combined Charging System Type 2 (CCS2, Combo2) from various brands to validate the interoperability among several vendors and support further EV integration with more affordable solutions. The optimization includes the calculation of the EBs’ consumption at various seasons and under various operating conditions in order to use optimum battery system design, heating system, optimum EB fleet operation and size and to find the charging solutions properly. The results showed that the EB consumption increases in some cases by 64.5% in wintertime due to heating systems, and the consumption in urban areas is more than that on the route lines outside cities. In the E-truck demo, where the electric heater was replaced with a heat-pump to optimize the energy consumption, it was found that the consumption of the heat-pump is about half of the electric heater under certain operating conditions. Under strict EB schedule, Pantograph charging solutions with power ratings of 300–600 kW have been adopted to charge the batteries of the EBs within 4–10 min. In order to minimize the cumulative costs of energy, (pantograph) charging infrastructure depreciation and battery degradation, as well as depot charging (at the bus operator’s depot), was adopted with a power level of 50–350 kW based on CCS2 and pantograph.

Experiments on Waste Heat Thermoelectric Generation for Passenger Vehicles

In order to utilize waste heat from passenger vehicles by a thermoelectric generator (TEG), a lab-scale TEG with a sufficient low-pressure drop was designed and tested. The waste heat from a 2.0 L petrol engine was simulated by using an air-circulation channel with an adjustable electric heater and a speed control motor. The TEG consisted of an integrated molding designed aluminum-finned heat collector, twenty thermoelectric modules, and a set of water-cooled heat sinks. Experiments were conducted in terms of power load feature, pressure drop, heat collection efficiency, thermoelectric efficiency and overall efficiency. It was found that the hot-end temperature was much lower (46.9%) than the flue gas temperature because the trade-off between fin area and pressure drop had to be considered. The obtained maximum electric power was 36.4 W, and the corresponding pressure drop was 36 Pa. The corresponding heat collection efficiency was 46.5%, and the thermoelectric efficiency was 2.88%, which agreed well with the theoretical prediction of 3.38%. As a result, an overall efficiency of 1.21% was reached. The present work firstly demonstrated a waste-heat-recovering TEG prototype with a balanced overall efficiency of over 1%, and a pressure drop of less than 50 Pa. On the other hand, the maximum electric power was difficult to fully extract. The charging power to a battery with a maximum power point tracking direct current–direct current converter was experimentally verified to work at a much higher conversion efficiency (15.3% higher) than regular converters.

Improving the unit for melting cheese masses

This paper reports the improved model of the unit for melting cheese masses. The device differs in the technique of heat supply to working tanks through the replacement of a steam jacket with heating by a flexible film resistive electric heater of radiative type (FFREhRT). The heat exchange surface of the working container was increased through heating the mixing device by FFREhRT. In addition, the unit is distinguished by utilizing secondary thermal energy of melting cheese masses (35...95 °C) by converting it with Peltier elements into a low-voltage power supply to autonomous fans (3.5...12 W) in order to cool the control unit. Such a solution would improve the efficiency of the proposed structure, which is explained by reducing the dimensional and weight parameters of the cheese melting unit by replacing the steam heating technique with an electric one. A decrease in the time to enter a stationary mode (85 °C) when melting cheese masses was experimentally confirmed: for the bowl of the examined unit ‒ 575 s, compared to the analog ‒ 725 s. That confirms the reduction in the time to enter a stationary mode by 21 % compared to the base unit B6-OPE-400. The estimation has established a 1.2-time decrease in the main indicator of resource efficiency of the specific energy consumption for heating the volume of a unit of product in the improved plant for melting cheese masses – 3,037.2 kJ/kg, compared to the base B6-OPE-400 – 3,672.5 kJ/kg. The results confirm an increase in resource efficiency that is achieved by the elimination of steam heat networks; the increased heat exchange surface of working bowls by heating the stirrer with the help of FFREhRT. The heat transfer that employs FFREhRT simplifies the operational indicators of the temperature stabilization system in the bowl of the cheese mass melting unit. The results reported here may prove useful when designing thermal equipment with electric heating while using secondary thermal energy.

Experimental investigation of desiccant dehumidification based thermoelectric air-conditioning system

Vapor compression refrigeration system (VCRS) based conventional cooling systems run on the high amount of electricity and refrigerants responsible for greenhouse emissions. To save the environment and high-grade energy, traditional cooling systems should be replaced with some environment-friendly alternative. This paper proposed alternative eco-friendly air-conditioning systems based on an amalgam of two different technologies, i.e., desiccant dehumidification and thermoelectric (TE) cooling. The proposed air-conditioning system has the following subprocess: dehumidification of moist air by the solid desiccant wheel, cooling of processed air by TE modules, and regeneration of desiccant wheel by an electric heater and waste heat from TE modules. The air conditioning system has been experimentally studied for cooling performance, cooling effect, and energy input. The maximum coefficient of performance of 0.865 can be achieved with the proposed system, and it can be used for cooling effects up to 1442.24 W to maintain the human comfort condition in the chamber i.e. approximately 22 ℃ and RH 50% defined by ASHRAE.

How to Adapt Mongolian Yurt to the Modern Requirements and European Climate—Airtightness versus CO2 Concentration?

There are currently trends in the world to transfer and adapt traditional solutions to contemporary needs. This applies, inter alia, to mobile shelters used by nomadic peoples. The article is devoted to the research on the quality of internal air in the yurt and the possibilities of its adaptation to high contemporary quality and environmental requirements, while maintaining its characteristic sustainable values. The tested traditional Mongolian yurt was moved from the dry and cold climate of the Asian steppe to the temperate climate of Central Europe and has been significantly modified. The outer shell materials have been changed, replacing natural materials with modern tight insulating foils. The wood-fired stove has been replaced with an electric heater and the roof opening has been firmly closed. All of these modifications resulted in far-reaching changes in the quality of the internal environment in the yurt. The conducted measurements and simulations of CO2 concentration in the modified yurt proved that the efficiency of ventilation system is not sufficient and that the air quality is very poor (even for a single user). In the case of a larger number of users, the concentration of CO2 has already reached a level that was dangerous to health. The simplest method of improving the air quality in the yurt is its careful unsealing to the required level. Striving for a low energy demand, however, would require a completely different approach (for example, in the form of forced ventilation with a heat recovery unit, ultimately powered with a PV array). Such a solution is very different from the traditional yurt model but is close to modern expectations and environmental requirements.

Effect of Temperature Variation of Static Thermal Tensioning on Angular Distortion and Sensitization behavior of GMAW Welded SUS 304 Stainless Steel Plate

Due to its rust resistance properties, the use of stainless steels, especially SUS304 for industrial equipment is increasing. The manufacturing process that is often used is GMAW welding. One of the disadvantages of SUS304 is the occurrence of distortion and sensitization when welded. In this study, the effect of temperature variations of Static Thermal Tensioning on angle distortion and microstructure behavior due to GMAW welding of SUS 304 T-joint plates was studied. Heating by electric heater is given to both parts of the base metal plate SUS 304 5mm thick with temperature variations of 200 oC, 250 oC and 300 oC. Cooling water with a temperature of 24 oC is provided on the back side of the welded track. Welding using filler ER 304 with a diameter of 0.8 mm with welding parameters such as welding current, voltage, gas flow and travel speed controlled at 75 A, 22 V, 10 l/min and 8 mm/s, respectively. Angular distortion of welding results for each treatment temperature variation was measured using a bevel protractor, and perform metallographic test to knowing the microstructural behavior. The results of the measurement of the average angular distortion of three repetitions show that at a temperature of 250 C static thermal tensioning produces the smallest angular distortion of 3ᵒ70', compared to other temperature variations which produce angular distortion 4o45’ at 200 oC and 3o86' at temperature 300 oC. The findings of the largest Cr (carbide) deposits due to sensitization were found at a temperature of 300 oC at 16,49% and the lowest at a temperature of 200 oC at 7,05%

Techno-Economic Study of a New Hybrid Solar Desalination System for Producing Fresh Water in a Hot–Arid Climate

By taking advantage of the obtained experimental data, the impact of employing concentrating solar collectors, using an electric heater, and changing the water height in the basin on the performance of a hybrid solar still system was investigated. Eight different operating modes for the system were studied, while the daily freshwater production in addition to the cost per liter (CPL) was considered as the performance criteria. According to the results, the best height of water in the basin is 10 mm. It is the lowest examined height. Moreover, it was found that using the hybrid system with both electric heater and concentrating solar heater brings considerable improvements compared to the other investigated operating modes. For the climatic condition of Sirjan, Iran, which is where the experiments were performed, and water height in the basin of 10 mm, using the hybrid system in the active mode results in 8178 mL/m2 of fresh water production, and a CPL of $0.04270 per liter.

Testing coffee roasting machine with electric heater as energy source

The roasting process is the process of frying something without using oil. The roasting processes raw materials into cooked or ready-to-eat ingredients. The purpose of the roasting is to get a certain taste using heat transfer methods either without media or using sand. When the roasting process occurs, the coffee beans undergo physical changes, one of which is the water content due to heat transfer from the roasting medium to the material. During the roasting process, evaporation of water content occurs and the coffee beans will experience a decrease in mass. Coffee bean roasting machines with stove heat sources from gas fuel are currently being developed. The use of gas fuel is sometimes difficult to regulate a constant temperature because it depends on the valve setting to exit the gas flow on the stove. On the other hand if incomplete combustion occurs it will affect the flavour of the roasted coffee beans. The purpose of this study was to test a coffee roasting machine with an electric element heat source. Roasting machine testing with a time of 50 minutes produces an average temperature of 196.64 °C with a final moisture content of 3.61%.

Capacity optimization of renewable energy microgrid considering hydropower cogeneration

This paper proposes a renewable energy system based on photovoltaic power generation, wind power generation and solar thermal power generation, combining thermal power plants with low-temperature multi-effect distillation. Through the electric heater and the thermal storage system photovoltaic and wind power will spare capacity in the form of heat energy, at the same time by thermal power generation system to maintain the stability of the power supply, run under constant output scheduling policy, to the levelling of the smallest energy cost and the design of power rate of maximum satisfaction as the goal, using multi-objective particle swarm optimization (PSO) algorithm to find the best combination of capacity, this system is established. At the same time, combined with low-temperature multi-effect distillation, compared with reverse osmosis seawater desalination cost is lower, reduce energy consumption, has a good application prospect.

Numerical optimization of a multistage sorption compressor

Sorption compressors are driven by thermal cycles and have no moving parts, excluding some passive check valves. Such compressors are suitable for powering Joule-Thomson (JT) cryocoolers and can provide reliable and vibration free active cooling system with a potential for high reliability and long operating life. The thermal cycle consists of cooling and heating a sorbent material which is installed in a sorption cell, where the heating is obtained by an inner electric heater and cooling is obtained by the surrounding via the sorption cell envelope. The investigation and optimization of the sorption cells were conducted in previous work, at steady state conditions, by a one-dimensional heat and mass transfer numerical model. The current paper presents a dynamic numerical model of sorption compressors which consist of several sorption cells. The numerical model allows one to three compression stages, with any number of sorption cells at each stage. The model enables the investigation of dimensional parameters and operational parameters, and provides the low and high pressures, pressure fluctuations, and compressor’s efficiency. The current investigation focuses on a three-stage compressor for nitrogen, with low and high pressures of 0.2 and 8 MPa, respectively, and a mass flow rate of about 11 mg/s.