Experimental study of the influence of glass cover cooling using evaporative cooling process on the thermal performance of single basin solar still

Acute shortage of drinking water has been on the rise owing to increasing population as well as shortage of drinkable water. Generation of potable water using passive solar stills is among the simplest and easier devices which make use of solar heat energy. However, the output of solar still is generally low owing to greater heat loss and needs improvement. In this paper, an experimental analysis is carried out to determine the performance of passive solar still with glass cover cooling using cold water generated using passive evaporative cooling process. The cold water required for cooling the glass cover is obtained using evaporative cooling process in the water tank which is wound with wet cotton cloth wick. The cold water thus obtained is sprayed onto the top surface of glass cover. The experiment is carried out in the outdoor conditions of Dubai from 10:00h to 14:00h and the temperature recordings of basin plate, glass cover, basin water, ambient air and cooling water are noted for every 30 minutes. The results reveal that the average increase in condensation heat transfer coefficient is found to be about 20.8% higher in the presence of glass cover cooling and the distillate output is found to increase by about 3.32 times. The average still efficiency is found to be relatively higher in the presence of cooling which is about 7.3% higher in the presence of cooling. The cold water temperature generated through evaporative cooling process is about 20.4% lower as compared to ambient temperature. Thus, the cooling of glass cover using cold water obtained through evaporative cooling process is found to be effective in enhancing the thermal performance of single basin solar still system

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely