A rigid copper tank, initially containing 2 m^3 of nitrogen…
A rigid copper tank, initially containing 2 m^3 of nitrogen at 300 K, 1 bar, is connected by a valve to a large supply line carrying nitrogen at 300 K, 20 bar. The valve is opened only as long as required to fill the tank with nitrogen to a pressure of 20 bar. Finally, the nitrogen in the tank is at 310 K. The copper tank, which has a mass of 10 kg, is at the same temperature of the air in the tank, initially and finally. The specific heat of copper is c = 0.385 kJ/kg/K. (a) Assuming ideal gas behavior of the nitrogen, determine the initial mass of nitrogen in the tank, in kg. m_1 = _______ kg. (b) Determine the final mass. m_2 = _______ kg. (c) Find the heat transfer to the surroundings from teh tank and its contents, in kJ, ignoring kinetic and potential energy effects. _______ kJ.
Read DetailsAn air compressor provides 6700 kW to raise air from an inle…
An air compressor provides 6700 kW to raise air from an inlet temperature T_1 = 300 K and inlet pressure p_1 = 1 bar to an outlet pressure T_2 = 620 K and outlet pressure p_2 = 12 bar. (a) What is the mass flow rate of air through the compressor, in kg/s? _______ kg/s. The air leaving the compressor flows through a regenerator, where it exchanges heat with a second air stream. The stream leaving the compressor leaves the regenerator at T_3 = 760 K and p_3 = 12 bar. The second air stream enters the regenerator at T_4 = 780 K and p_4 = 1 bar. Its mass flow rate, m_dot_4, is double the mass flow rate of the stream flowing through the compressor. (b) Find the temperature, T_5. Use linear interpolation to obtain an answer that is accurate to 0.1 K. _______ K.
Read DetailsA direct contact heat exchanger (mixer) operates at a fixed…
A direct contact heat exchanger (mixer) operates at a fixed pressure of p = p_1 = p_2 = p_3 = 25 bar with a working fluid of water. One stream of water enters at T_1 = 35 deg C and pressure p_1 = 25 bar. A second stream enters at p_2 = 25 bar and a quality x_2 = 0.50. The well-mixed streams leave as a saturated liquid at p_3 = 25 bar. Find the mass flow rate of stream 2. m_dot_2 = _______ kg/s.
Read DetailsUse the following patient vignette to answer questions 11 –…
Use the following patient vignette to answer questions 11 – 13. A 35-year-old man presents with a sputum-producing cough and dyspnea at rest. Past medical history is significant for a previous diagnosis of premature emphysema at age 28. The patient denies smoking and excessive alcohol intake or exposure to dust and mold. Family history is significant for coronary artery disease and pulmonary disease in the patient’s father and only brother. Vital signs are within normal limits except for blood pressure of 160/120 mmHg on three readings. Physical examination reveals an ill-appearing man with prolonged expiratory time. Auscultation of the lungs reveals end-expiratory wheezing. ECG is within normal limits. Which of the following is the most likely risk factor/predisposing condition for this patient’s illness?
Read DetailsUse the following patient vignette to answer questions 1-3….
Use the following patient vignette to answer questions 1-3. 1. Mr. Cheeseman is a 55-year-old man. He has been a pack-a-day smoker since the age of 20. He undergoes a pulmonary function test. Which of the following changes are most consistent with his diagnosis of Emphysema? FEV1 FEV1/FVC A. Low High B. Low Low C. High High D. High Low
Read DetailsUse the following patient vignette to answer questions 25 –…
Use the following patient vignette to answer questions 25 – 26. A 52-year old man arrives at your office complaining of dyspnea at rest and a non-productive cough. He states his cough has gotten worse over the past few months. He has been smoking 1 pack a day for the past 35 years and states he only has an occasional glass of wine at dinner. His family history is significant for pancreatic cancer. He complains that he has had trouble sleeping, has been very tired all the time, and has abnormal muscle cramping. Upon physical examination, you observe mild digital clubbing. You order a CT and find extensive honeycombing present at both lung bases. Which of the following is the most likely diagnosis for this patient?
Read DetailsUse the following patient vignette to answer questions 7 – 8…
Use the following patient vignette to answer questions 7 – 8. A 65-year-old woman is evaluated for a week-long fever, productive cough with purulent sputum, and increasing dyspnea. She smokes one pack of cigarettes a day. Her medical history includes hypertension and hypercholesterolemia, for which she is treated with simvastatin, hydrochlorothiazide, and aspirin. On physical examination, the patient is in mild respiratory distress. Temperature is 38.5°C (101.3°F), blood pressure is 145/85 mm Hg, pulse rate is 92/min, and respiration rate is 21/min; BMI is 28. Oxygen saturation is 92% with the patient breathing ambient air and 95% on oxygen, 2 L/min by nasal cannula. Pulmonary auscultation reveals bilateral expiratory wheezes and rhonchi. Physical exam reveals no digital clubbing but 1+ ankle edema. Lips are slightly bluish. Chest radiograph shows increased bronchovascular markings. Laboratory values indicate normal CBC, except for an increase in neutrophils and hemoglobin. Arterial blood gases, while the patient was breathing ambient air, are pH 7.40, PCO2 41 mm Hg, and PO2 53 mm Hg. Spirometry shows an FEV1 of 45% of predicted and an FEV1/FVC ratio of 52%. 8. What is the best management plan for this patient?
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