Due to the growing demand for refrigerators and air conditioners in automobiles, there is a need for an innovative and efficient design to achieve both refrigeration and air conditioning. To address this, the present work has evaluated a two-evaporator vapor compression system to eliminate the requirement for separate refrigeration and air conditioning units. Theoretical energy and exergy performance assessment of the same is carried out along with the variation in the condenser and evaporators temperature. Various low GWP refrigerants such as R1234yf, HFO1336mzz(Z), R513A, and R450A are compared against high GWP R134a and R452A. The results reveal that maximum exergy efficiency and COP and lowest compressor power of 31.50%, 2.47, and 6.304 kW, respectively, are obtained with HFO1336mzz(Z). After HFO1336mzz(Z), R134a shows the highest exergy efficiency and COP of 30.56% and 2.41, respectively, and the lowest compressor power of 5.61kW. HFO1336mzz(Z) exhibits the optimum performance, whereas R452A shows the worst thermodynamic performance in the system. It is also found that the performance of R450, R513A, R450A, and R1234yf is approximately equivalent to each other. Moreover, component-wise exergy destruction analyses indicate that the efficiency of the compressor needs to be improved as the maximum destruction of 61.84–56.00% occurs in the compressor while the minimum exergy destruction of 0.42–0.54% occurs in the expansion valve. This study proposes the two-evaporator system for both refrigeration and air conditioning in automobiles. It is also found that R450A, R1234yf, R513A, and HFO1336mzz(Z) can be the potential alternative to R134a.
Reading speed has long been recognized in scholarly literature as an essential component of reading fluency and successful reading. A variety of instructional techniques and activities are used to improve reading speed of learners. Sustained Silent Reading (SSR) is one such way that encourages the development of reading fluency and reading speed. This study investigated the impact of SSR on reading speed of female Pakistani EFL learners. A nine-week long SSR program was designed with 10 minutes timed-reading activity to improve students’ reading rate. Using random sampling procedures, fifty female students were selected to participate in the study. After the pre-test, twenty five students were kept in treatment group and twenty five in control group. Results of the study show that the experimental group’s average reading speed considerably increased from 115.60 wpm to 347.60 wpm after the intervention which indicates positive impact of SSR on reading speed of the participants. Statistically significant differences were found in reading rate gains between the two groups. Interestingly, a slight increase was also noted in the reading speed of students in the control group. The findings of the study indicate that SSR is a very effective instructional technique in developing EFL learners’ reading rate. Keywords: Reading rate, Fluency, Sustained Silent Reading, Reading fluency, EFL learners, Pakistan
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