활동

Bus HVAC energy consumption test method based on HVAC unit

In this study, passenger comfort and the air pollution status of the micro-environmental conditions in an air-conditioned bus were investigated through

questionnaires, field measurements, and a numerical simulation. As a subjective analysis, passengers' perceptions of indoor environmental quality and

comfort levels were determined from questionnaires. As an objective analysis, a numerical simulation was conducted using a discrete phase model to determine

the diffusion and distribution of pollutants, including particulate matter with a diameter air quality and dissatisfactory thermal comfort conditions in

Jinan's air-conditioned bus system. To solve these problems, three scenarios (schemes A, B, C) were designed to alter the ventilation parameters.

According to the results of an improved simulation of these scenarios, reducing or adding air outputs would shorten the time taken to reach steady-state

conditions and weaken the airflow or lower the temperature in the cabin. The airflow pathway was closely related to the layout of the air conditioning.

Scheme B lowered the temperature by 0.4 K and reduced the airflow by 0.01 m/s, while scheme C reduced the volume concentration of PM 10 to 150 μg/m 3 .

Changing the air supply angle could further improve the airflow and reduce the concentration of PM 10 . With regard to the perception of airflow and thermal

coA system of air-conditioning using Lithium Bromide absorption system is used as an alternative refrigerant that will not pollute the atmosphere. Lithium

Bromide is a chemical salt soluble in water. 

There is a big difference between vapour compression system and LiBr 2 absorption system. The absorption air conditioning system is made of a generator,

a condenser, an evaporator and an absorber with necessary pumps and piping. When LiBr 2 solution is heated under low pressure, water will evaporate first,

while LiBr 2 will remain in the solution and will become more concentrated. The water is the refrigerant in this system. The generator, where the water is

vapourised, is heated using an electric heater or solar energy. The LiBr 2 weak solution under low pressure in the generator is heated and the water

evaporate into vapour. The vapour produced is then cooled in the condenser and then expanded into the evaporator. The refrigerant (water) in evaporator

change phase from liquid to vapour by absorbing heat from cooling water, which flow in the coil in the evaporator. The chilled water obtained is then pumped

into the fan coil, which will be used in conditioning the passenger area of the bus. The water vapour from the evaporator is absorbed into LiBr 2 solution in

the absorber, forming a weak solution of LiBr 2 . the weak solution from the absorber is then pumped back to the generator to regenerate. The absorption

system does not use compressor, but requires pumps that need lower input power compared to that of a compressor. The system is considered as a new

application for the bus. This will have great potential and will be environmentally friendly. The model in this study will be used for calculation of the

cooling load for the bus.

Comfortable journey with commercial buses is an essential goal of transportation companies. An air-conditioning system can play an important role for

this comfortable journey but it can put extra load on the engine and extra cost in the fuel consumption. The purpose of this work is to increase the

performance of air-conditioning system of the buses by reducing the load on the engine and fuel consumption. Using a two-phase ejector as an expansion valve

can increase the coefficient of performance (COP) of the air-conditioning system. An improvement in the COP can reduce the empty vehicle weight and fuel

consumption of buses. Two-phase ejector dimensions can be determined using the empirical methods available in the literature. In this paper, the two-phase

ejector dimensions of air conditioning system for a bus are calculated using the analytical and numerical methods. First of all, the thermodynamic analysis

of the vapor-compression refrigeration cycle with a two-phase ejector is performed, and then the ejector dimensions are subsequently determined. The cooling

loads of the midibus and bus with R134a as a refrigerant are assumed to be 14Â kW and 32Â kW, respectively. The total length of the two-phase ejector for the

midibuses and buses due to these cooling loads, are computed to be 480.8Â mm and 793.1Â mm, respectively. Also, an experimental setup is installed on a truck air conditioner to turn it into the ejector air conditioning system to

validate theoretical results with the experimental study. – Highlights: • Determination of two-phase ejector dimensions of a bus air-conditioning system.

• Thermodynamic analysis of the two-phase ejector cooling system.