Termodinâmica - Atividade Resolvida sobre Ciclos e Eficiência de Motores

ATIVIDADE AS RESPOSTAS DEVEM SER APRESENTADAS À CANETA Questão 1 Um motor de automóvel funciona em regime permanente desenvolvendo uma potência de 200 HP veja a figura 1 Conhecendose os seguintes elementos característicos do seu funcionamento determine o consumo horário de combustível kgh a variação de entropia no motor kcalhK a taxa de calor perdida kcalh e o índice de eficiência deste motor Desprezar a potência elétrica para o acionamento da bomba Adote 1 HP 6408 kcalh calor específico da água 1 calgºC densidade 097 kgl Questão 2 Na figura 2 é representando um ciclo de potência de vapor com reaquecimento conhecido como Rankine Alguns dados operacionais do ciclo estão indicados na tabela Considerandose desprezíveis as variações de energia cinética e potencial determine para a água como fluido de trabalho e com uma vazão de 250 kgmin a temperatura na saída da bomba as irreversibilidades dos mecanismos quando houver a taxa de calor que entrou no ciclo e a eficiência térmica do ciclo Questão 3 Um carro possui um motor com eficiência térmica de 35 Assumese que o ar condicionado tenha um COP de 33 trabalhando para refrigerar o interior utilizando parte do trabalho produzido Qual seria a energia extra de combustível para se retirar 170 kJ do interior do carro Questão 4 Na figura 3 assumindose que todos os processos são reversíveis como seria sua análise sobre a máquina R segundo as leis termodinâmicas Justifique a sua resposta Questão 5 Considere o turbocompressor de um motor a combustão interna onde os gases de exaustão entram na turbina a 450ºC a uma vazão de 002 kgs e saem a 400ºC figura 4 O ar entra no compressor a 70ºC e 95 kPa e sai a uma vazão de 0018 kgs a 135 kPa A eficiência mecânica entre a turbina e o compressor é de 95 Usando Água de refrigeração do motor Entalpias kcalkg Temperatura ºC à 200 kPa Ar har 7 Entrada Saída Gases hg 22 40 80 Combustível hc 7800 Temperatura média de operação do motor Tm 180ºC Vazão volumétrica na bomba de água de 05 litros por segundo Relação entre consumo de ar e do combustível ṁarṁc 18 PONTO T ºC P kPa h kJkg 1 10 2 19975 3 520 5000 4 2000 335748 5 349052 6 245000 Figura 1 Figura 2 Figura 3 300ºC M 42ºC Q1 Q2 R 344 K Q3 Q4 W as propriedades do ar para os gases de exaustão determine a temperatura de saída e a irreversibilidade no compressor Questão 6 As necessidades de água potável de uma instalação com 20 funcionários devem ser atendidas por um bebedouro figura 5 O bebedouro refrigerado deve resfriar de 22ºC para 8ºC e fornecer água gelada a uma taxa de 04 litros por hora por pessoa Calor é transferido para o reservatório da vizinhança a 25ºC a uma taxa de 45 W Se o COP do sistema de refrigeração for 29 determine o tamanho em W do compressor adequado ao sistema de refrigeração desse bebedouro Figura 4 Figura 5 QUESTÃO 1 Fazendo o balanço de energia no motor 𝑚𝐶ℎ𝐶 𝑚𝑎𝑟ℎ𝑎𝑟 𝑚á𝑔𝑢𝑎ℎá𝑔𝑢𝑎1 𝑚á𝑔𝑢𝑎ℎá𝑔𝑢𝑎2 𝑚𝑔𝑎𝑠𝑒𝑠ℎ𝑔𝑎𝑠𝑒𝑠 𝑊𝑚𝑜𝑡𝑜𝑟 𝑚𝐶ℎ𝐶 𝑚𝑎𝑟ℎ𝑎𝑟 𝑚á𝑔𝑢𝑎 ℎá𝑔𝑢𝑎1 ℎá𝑔𝑢𝑎2 𝑚𝑔𝑎𝑠𝑒𝑠ℎ𝑔𝑎𝑠𝑒𝑠 𝑊𝑚𝑜𝑡𝑜𝑟 𝑚á𝑔𝑢𝑎 05𝐿 𝑠 3600𝑠 1ℎ 097𝑘𝑔 1𝐿 1746 𝑘𝑔ℎ 𝑚𝐶 7800 18𝑚𝑐 7 1746 40 1746 80 19𝑚𝑐 22 200 6408 7800𝑚𝑐 126𝑚𝑐 69840 139680 418𝑚𝑐 128160 𝑚𝑐 2637 𝑘𝑔ℎ A taxa de calor perdida 𝑄 𝑚á𝑔𝑢𝑎 𝑐𝑝 𝑇2 𝑇1 𝑄 1746 1 80 40 𝑄 69840 𝑘𝑐𝑎𝑙ℎ O índice de eficiência do motor 𝜂 200 6408 2637 7800 𝜂 6231 A variação da entropia Δ𝑆 𝑄 Δ𝑇 Δ𝑆 69840 40 Δ𝑆 1746 𝑘𝑐𝑎𝑙ℎ WHEN YOURE AT THE TOP OF YOUR GAME BUT YOUR FOOD BINDS YOU DOWN WE HELP YOU FIND RELIEF DiaTribe Foundation To learn more visit diaTribeorgBetterDigestiveHealth or scan the QR code to access a dedicated page with additional resources and information about diabetes and chronic digestive symptoms like gastroparesis Do you have diabetes and digestive symptoms such as bloating nausea heartburn early fullness pain vomiting or diarrhea You might have gastroparesis a chronic diabetes complication that disrupts digestion Gastroparesis can worsen blood sugar control and cause malnutrition hospitalization anxiety and stress Dont suffer in silence Your symptom story matters Talk to your healthcare team about your symptoms and ask if you might have gastroparesis The symptoms of gastroparesis can look like the symptoms of many other common conditions such as irritable bowel syndrome IBS acid reflux GERD eating disorders or medication side effects You may need tests like a gastric emptying study to confirm gastroparesis Dont ignore your symptom story Getting the right diagnosis will help you get proper treatment improve your blood sugar control and improve your quality of life Learn about the resources that can help you find relief FRIENDS FAMILY HEALTHCARE PROVIDERS PROVIDERS TOOLS TIPS There are ways to manage gastroparesis usually including dietary changes medication and other treatment options Learn more about these options to help you discuss an individualized treatment plan with your healthcare team Other organizations with helpful gastroparesis information and support American Diabetes Association ADA diabetesorgPAD 1800DIABETES American College of Gastroenterology ACG giorg 8474275561 Gastroparesis Patient Association for Cures and Treatments GPACT gastroparesisorg 8777002473 Thank you to our advisory panel and corporate supporters for their assistance with this guide Learn more at diaTribeorgBetterDigestiveHealth DiaTribe Foundation 2020 Front image iStocksofiko1986 This resource was made possible by a charitable grant from Vifor Pharma and AbbVie Cover graphic design Ashley Bourgeois Check this out Videos and a webinar about living with gastroparesis diaTribeorgVideosGastroparesis Digestion videos from diaTribe and Grayson Chase diaTribeorgDayOfDiabetes More information about diabetes complications and digestive symptoms such as gastroparesis diaTribeorgGastroparesis Scan or click the QR code to access these resources online Jamal Ibdah MD Scripps KIman Merchant DO Vifor Pharma Satish Rao MD Augusta University David Levin MD DiaTribe Midori N Snyder RN Volition America Lisa Dice MBA DiaTribe Mary Raithatha RD CDCES DiaTribe Stephanie Siebold MMath DiaTribe Alan Palkowitz MD Diabetes Treatment Centers of America DTCA Linda GonderFrederick PhD University of Virginia Roger Jenkins MD Emory the b es the on e e on l e a veo l d r y pro DIABETES PATIENTS The following health professionals reviewed the patient materials Kelly Gibas MD Thomas Jefferson University Jennifer Chu MD Mount Sinai Satish Rao MD Augusta University Jennifer Pruszynski MD Cleveland Clinic Holly Harbison MD UT Health Michael Camilleri MD Mayo Clinic This infographic is for educational purposes only and is not intended to provide medical advice or support Please talk to your healthcare professionals about your individual situation and treatment Other organizations with helpful gastroparesis information and support American Diabetes Association ADA diabetesorgPAD 1800DIABETES American College of Gastroenterology ACG giorg 8474275561 Gastroparesis Patient Association for Cures and Treatments GPACT gastroparesisorg 8777002473 DiaTribe Foundation 2020 All rights reserved DiaTribe Foundation diaTribeorg Better health through empowerment Q A 148 083020 The DiaTribe Foundation is a 501c3 nonprofit organization Read our privacy notice at diaTribeorgprivacy DiaTribe Foundation is not affiliated with any pharmaceutical company The views expressed here are those of authors and editors only not of any pharmaceutical or medical device companies The above information is not intended to replace medical advice from your healthcare provider Always talk to your healthcare provider about your own health and treatment Visit DiaTribeorg for more options to discuss diabetes complications and symptoms Dietary changes Medication Treatment options DiaTribe Foundation diaTribeorgBetterDigestiveHealth Day 9 of 12 New start by eating less and often TO HELP WITH YOUR DIGESTIVE SYMPTOMS Eat at least six small meals daily each about the size of your fist Eat slowly chewing thoroughly Avoid carbonated and sugary beverages such as soda Limit alcohol and smoking Avoid highfat highfiber foods such as fried foods nuts seeds popcorn and raw vegetables Drink plenty of water each day and avoid liquids 30 minutes before and after meals Try to rest or lightly walk for 20 minutes after eating Scan or click the QR code to access videos about gastroparesis and living well DiaTribe Foundation 2020 diaTribeorg Better health through empowerment y Digestive health matters Learn more about diabetes and chronic digestive symptoms such as gastroparesis by visiting diaTribeorgBetterDigestiveHealth Youre not alone If you have diabetes and digestive symptoms such as bloating nausea heartburn early fullness pain vomiting or diarrhea learn about gastroparesis a common chronic diabetes complication Gastroparesis disrupts digestion when the stomach takes too long to empty food or does not empty properly The symptoms of gastroparesis can be very similar to other conditions so getting an accurate diagnosis is important Gastroparesis symptoms include early fullness bloating nausea vomiting abdominal pain or discomfort acid refluxheartburn diarrhea or constipation Gastroparesis can worsen blood sugar control increase hospitalizations lead to malnutrition or weight loss increase anxiety and stress DiaTribe Foundation 2020 This resource was made possible by a charitable grant from Vifor Pharma and AbbVie This infographic is for educational purposes only and is not intended to provide medical advice or support Please talk to your healthcare professionals about your individual situation and treatment Gastrointestinal GI Study provides strong evidence that mild anemia associated with type 2 diabetes mellitus US National Library of Medicine State University of New York Downstate Health Sciences University May 27 2021 We aimed to clarify the effect of mild anemia on the incidence of diabetic peripheral neuropathy DPN and diabetic kidney disease to elucidate the relationship between mild anemia and DPN or kidney disease in diabetic patients We analyzed 883 patients with type 2 diabetes mellitus Patients with anemia displayed significantly lower monofilament test scores prolonged minimum Fwave latency an abnormality of tibial nerves and higher urinary albumin levels than nonanemic patients Monofilament test is a simple clinical test commonly used to evaluate DPN Urinary albumin and minimum Fwave latency are indices of diabetic kidney disease and diabetic peripheral neuropathy respectively Mild anemia was independently associated with DPN and diabetic kidney disease after adjustement for confounding factors such as diabetes duration and glycemic control Patients with type 2 diabetes mellitus accompanied with mild anemia should undergo screening examinations to evaluate DPN and diabetic kidney disease at an early stage and should be carefully followed up thereafter Review of Study by Mariko Iwakura MD Checked by Ataru Shimozuma MD and Rie Takahashi PharmD PhD The above information does not replace medical advice from your healthcare provider Always talk to your healthcare provider about your own health diaTribeorg QUESTÃO 2 PONTO 1 Líquido Saturado 𝑇1 4581 ℎ1 19183 𝑘𝐽𝑘𝑔 𝑣1 0001010 𝑚3𝑘𝑔 PONTO 2 Líquido Comprimido 𝑇2 4666 ℎ2𝑠 19741 𝑘𝐽𝑘𝑔 A eficiência isentrópica da bomba 𝜂𝐵 19741 19183 19975 19183 0704 A irreversibilidade da bomba será 𝐼𝐵 296 PONTO 3 Vapor Superaquecido ℎ3 348035 𝑘𝐽𝑘𝑔 𝑠3 70342 𝑘𝐽𝑘𝑔𝐾 PONTO 4 Vapor Superaquecido PONTO T ºC P kPa h kJkg s kJkgK 1 4581 10 19183 06493 2 4666 5000 19975 06493 3 520 5000 348035 70342 4 2000 335748 70342 5 51032 2000 349052 74595 6 10 245000 74595 ℎ4𝑠 318748 𝑘𝐽𝑘𝑔 A eficiência isentrópica do primeiro estágio da turbina 𝜂𝑇1 335748 348035 318748 348035 0419 A irreversibilidade do primeiro estágio da turbina será 𝐼𝑇1 581 PONTO 6 Vapor Saturado 𝑠6𝑠 𝑠𝑙 𝑥 𝑠𝑙𝑣 74595 06492 𝑥6 75010 𝑥6 0908 ℎ6𝑠 ℎ𝑙 𝑥 ℎ𝑙𝑣 ℎ6𝑠 19181 0908 239282 ℎ6𝑠 236449 𝑘𝐽𝑘𝑔 A eficiência isentrópica do segundo estágio da turbina 𝜂𝑇2 245000 349052 236449 349052 0924 A irreversibilidade do segundo estágio da turbina será 𝐼𝑇2 76 A taxa de calor que entrou no ciclo 𝑄𝐵 𝑚 ℎ3 ℎ2 𝑄𝐵 250 60 348035 19975 𝑄𝐵 1366917 𝑘𝑊 A eficiência térmica do ciclo 𝜂𝑐𝑖𝑐𝑙𝑜 𝑊𝑇 𝑊𝐵 𝑄𝐵 𝜂𝑐𝑖𝑐𝑙𝑜 250 60 335748 348035 2450 349052 250 60 19975 19183 1366917 𝜂𝑐𝑖𝑐𝑙𝑜 3522 QUESTÃO 3 O trabalho produzido pelo carro 𝑊 𝜂𝑀 𝑄𝑐𝑜𝑚𝑏 O trabalho utilizado pelo ar condicionado 𝑊 𝑄𝐿 𝐶𝑂𝑃 Igualando as duas equações 𝜂𝑀 𝑄𝑐𝑜𝑚𝑏 𝑄𝐿 𝐶𝑂𝑃 𝑄𝑐𝑜𝑚𝑏 𝑄𝐿 𝜂𝑀 𝐶𝑂𝑃 Substituindo 𝑄𝑐𝑜𝑚𝑏 170 035 33 𝑄𝑐𝑜𝑚𝑏 14719 𝑘𝐽 QUESTÃO 4 A eficiência da máquina M 𝜂𝑀 1 42 273 300 273 45 A eficiência da máquina R 𝜂𝑅 1 42 273 344 84 A máquina R não precisa receber trabalho para seu funcionamento uma vez que é uma máquina térmica e que está removendo calor da fonte quente e transferindo para a fonte fria A eficiência da máquina R é menor do que a da máquina M QUESTÃO 5 Na temperatura média do ar de 425 ºC 𝐶𝑃 1075 𝑘𝐽𝑘𝑔𝐾 ℎ𝑎𝑟 400 68434 𝑘𝐽𝑘𝑔 ℎ𝑎𝑟 450 73806 𝑘𝐽𝑘𝑔 Calculando o trabalho produzido na turbina 𝑊𝑇 𝑚 ℎ𝑎𝑟400 ℎ𝑎𝑟450 𝑊𝑇 002 68434 73806 𝑊𝑇 1074 𝑘𝑊 Cálculo do trabalho no compressor 𝑊𝐶 𝑊𝑇 𝜂 𝑊𝐶 1074 095 𝑊𝐶 1020 𝑘𝑊 Calculando a entalpia de saída do ar no compressor 𝑊𝐶 𝑚 ℎ𝑠𝑎í𝑑𝑎 ℎ𝑒𝑛𝑡𝑟𝑎𝑑𝑎 ℎ𝑒𝑛𝑡𝑟𝑎𝑑𝑎 34344 𝑘𝐽𝑘𝑔 1020 0018 ℎ𝑠𝑎í𝑑𝑎 34344 ℎ𝑠𝑎í𝑑𝑎 40011 𝑘𝐽𝑘𝑔 Pela tabela termodinâmica encontrase a temperatura correspondente à esta entalpia 𝑇 12614 Calculando a temperatura isentrópica do compressor 𝑇4𝑠 𝑇3 𝑝4 𝑝3 𝑘1 𝑘 𝑇4𝑠 343 135 95 141 14 𝑇4𝑠 10622 A eficiência isentrópica do compressor 𝜂𝐶 𝑇4𝑠 𝑇3 𝑇4 𝑇3 𝜂𝐶 10622 70 12614 70 𝜂𝐶 6452 QUESTÃO 6 Calculando a carga total de calor que deverá ser retirado da água 𝑄 𝑚 𝑐𝑝 𝑇 𝑄 04 3600 20 4180 22 8 𝑄 13004 𝑊 A carga total de calor sendo retirado 𝑄𝑇 13004 45 𝑄𝑇 17504 𝑊 Calculando o trabalho do compressor 𝐶𝑂𝑃 𝑄𝑇 𝑊 29 17504 𝑊 𝑊 6036 𝑊