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This study aimed to investigate the effect of changing the indoor unit air flow rate on the performance of an automobile heat pump with a suction line heat exchanger. Using a four-way valve, the automotive heat pump system was developed by reversing the refrigerant direction in the automobile air conditioning system, excluding the compressor. A suction line heat exchanger was added to the test system to enhance heat transfer between the liquid and suction lines of the automotive heat pump system. Performance comparisons were first performed for R134a and R1234yf by disabling the suction line heat exchanger. Then, the suction line heat exchanger was activated for R1234yf, and the tests were repeated. Performance comparisons were made for two different compressor speeds and three different indoor unit airflow speeds. It was found that using the heat exchanger in R1234yf operations improved the heating capacity, compressor discharge temperature and coefficient of performance by approximately 1.8 %, 5.1 % and 5.9 %, respectively. The heating capacity of the heat pump system using R134a, R1234yf, and R1234yf with the suction line heat exchanger was determined to be in the range of 2.46-3.29 kW, 2.35-3.04 kW, and 2.39-3.11 kW, respectively. An increase in the airflow speed of the indoor unit from 1.4 m s -1 to 3.2 m s -1 resulted in an average decrease of approximately 12.3 % in the compressor discharge temperature. In contrast, the heating capacity and coefficient of performance increased by approximately 11.8 % and 14.4 % on average, respectively, for R1234yf operations with the heat exchanger. This study revealed that by optimizing the air flow rate in the R1234yf heat pump system with a suction line heat exchanger, improvements in the heating capacity and coefficient of performance can be achieved, thus providing better thermal comfort in the passenger compartment., Competing Interests: The author declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author.)

Objectives: The aim of this study was to evaluate the neutrophil-to-lymphocyte ratio (NLR) and the mean platelet volume (MPV) in patients with active thyroid orbitopathy (TO) and to compare it with that of both healthy subjects and patients with inactive TO., Methods: Twenty patients with active TO (Group 1), 25 patients with inactive TO (Group 2), and 35 age- and sex-matched healthy subjects (Group 3) were included in this study. Patients with other systemic and ocular diseases, patients with a history of intraocular or orbital surgery, and patients using systemic drugs were excluded. The VISA (vision, inflammation, strabismus, appearance) classification scheme was used to discriminate between active and inactive TO. The neutrophil and lymphocyte counts and the MPV of all participants were recorded. The NLR was calculated by dividing the neutrophil count by the lymphocyte count, and the result was compared between groups. The optimal cut-off value was determined for NLR and MPV and the data were compared with a one-way analysis of variance test and the 'Bonferroni post-test., Results: The mean age was 45.4±13.4, 41.0±13.7, and 42.6±14.4 years in Group 1, 2, and 3, respectively (p=0.68). The NLR was 2.11 in Group 1, 1.56 in Group 2, and 1.47 in Group 3 (p=0.03). The 'Bonferroni post-test revealed a difference between Group 1 and Group 2 (p=0.01) and between Group 1 and Group 3 (p<0.001). The MPV was 10.76 fL in Group 1, 9.94 fL in Group 2, and 8.19 fL in Group 3 (p<0.001). The results of the 'Bonferroni post-test showed a difference between Group 1 and Group 2 (p=0.04), between Group 1 and Group 3 (p<0.001), and between Group 2 and Group 3 (p<0.001). The mean cut-off value obtained from receiver operating characteristic (ROC) analysis of NLR was 1.69 (sensitivity: 72%; specificity: 66%). The mean cut-off value obtained from ROC analysis of MPV was 9.95 (sensitivity: 63%; specificity: 66%)., Conclusion: High NLR and MPV values may be indicative of active inflammation in patients with TO.", Competing Interests: Conflict of Interest: None declared., (Copyright: © 2018 by The Medical Bulletin of Sisli Etfal Hospital.)