In the present work, exergy analysis has been experimentally evaluated for a chest freezer to assist in sizing calculations and selecting the most suitable working fluid, which can reduce the power consumption. In the present work, exergy analysis has been experimentally evaluated for a chest freezer to assist in sizing calculations and selecting the most suitable working fluid to reduce power consumption. The experimental measurements were carried out using a 150 litters chest freezer volume capacity running on R-134a and R-600a using different compressors. The freezer provides measurement instruments for pressure, temperature, refrigerant mass flow and power consumption. The tests were carried out with a standard ambient temperature of 32. The results show that the evaporator had the highest exergy loss value of 59% for R-134a and 62% for R-600a. Compressor exergy losses are 64% for R-134a and 63% for R-600a. The condenser showed exercise losses of 79% for R-134a and 75% for R-600a, while the limitation device (capillary tube) had exercise losses of 87% for R134a and 99.5% for R-600a. The thermal performance of the chest freezer represented by the second low efficiency is 43% for R-134a and 50% for R-600a. The thermal performance of the freezer with R-600a is better than R-134a due to the energy consumption reducing and evaporator behaviour.

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Objectives: To determine the role of Supraclavicular Artery Island Flap as analternate to local and other regional flaps for complex soft tissue reconstruction of head and neckdefects created by tumor resection, fire arm injuries, and burns. Study Design: A descriptiveclinical experimental study. Place and Duration of Study: From December 2014 to November2017, at Department of Plastic & Reconstructive Surgery, Dow University of Health Sciencesand Dr. Ruth KM Pfau, Civil Hospital Karachi, Pakistan. Methodology: Pedicle supraclavicularartery island flap was used to reconstruct facial soft tissue defects. Recipient and donor siteoutcomes, functional consequences and complications were assessed. Patients with soft tissuedefects either due to tumor extirpation and supraomohyoid neck dissection, trauma due tofirearm arm and burn were included. Patients with level IV neck dissection or having scarred orinjured supraclavicular areas were excluded. Results: Eighty-Four Supraclavicular Artery Islandflap reconstructions were performed for the reconstruction of lower face defects. Mean age ofpatients was 40.7 years. Through-and-through defect involving the oral lining and skin of thelower face after tumor excision in 78 cases, fire arm injury and burn was the cause in3patientseach. Complete flap failure was 3 (3.5%) and partial flap failure was in 6 (7.1%) patients. Meanperiod of follow-up was 11.86 months (range 7-19 months). Conclusion: Supraclavicular ArteryIsland Flap is an excellent alternate to other local and regional flaps with impressive recovery,acceptable skin color match and restoration of anatomic function at recipient site without anyserious complications. Majority of donor sites were closed primarily, and healed without anymajor complications.