Literature reveals that ice has always been available to aristocracy who could afford it. Later on, cork was used as insulating material. Materials like sawdust or wood shavings were used as insulating materials in these icehouses. In Europe, America and Iran a number of icehouses were built to store ice.
Made during night by cooling of water by radiation to stratosphere. Harvested in winter and stored in ice houses for summer use or, 3. Natural Refrigeration In olden days refrigeration was achieved by natural means such as the use of ice or evaporative cooling. Q: Which of the following can be called as a refrigeration process? a) Cooling of hot ingot from 1000oC to room temperature b) Cooling of a pot of water by mixing it with a large block of ice c) Cooling of human beings using a ceiling fan d) Cooling of a hot cup of coffee by leaving it on a table e) Cooling of hot water by mixing it with tap water f) Cooling of water by creating vacuum over itġ.2.
Here we present only aīrief history of the subject with special mention of the pioneers in the field and some important events. The French scientist Roger ThÝvenot has written an excellent book on the history of refrigeration throughout the world. The history of refrigeration is very interesting since every aspect of it, the availability of refrigerants, the prime movers and the developments in compressors and the methods of refrigeration all are a part of it. The subject of refrigeration and air conditioning has evolved out of human need for food and comfort, and its history dates back to centuries. Air Conditioning refers to the treatment of air so as to simultaneously control its temperature, moisture content, cleanliness, odour and circulation, as required by occupants, a process, or products in the space. Refrigeration systems are also used extensively for providing thermal comfort to human beings by means of air conditioning. One of the most important applications of refrigeration has been the preservation of perishable food products by storing them at low temperatures. Introduction Refrigeration may be defined as the process of achieving and maintaining a temperature below that of the surroundings, the aim being to cool some product or space to the required temperature. Name important landmarks in the history of refrigerationġ.1. List salient points of various refrigeration techniques, and 3. Identify various natural and artificial methods of refrigeration 2. Vortex tubes (Section 1.3.7) At the end of the lesson the student should be able to: 1. Thermoelectric refrigeration systems (Section 1.3.6), and g. Steam and vapor jet refrigeration systems (Section 1.3.5) f. Air cycle refrigeration systems (Section 1.3.4) e. Solar energy based refrigeration systems (Section 1.3.3) d. Vapour absorption refrigeration systems (Section 1.3.2) c. Air conditioning systems (Section 1.3.1.2) b. Domestic refrigeration systems (Section 1.3.1.1) ii. Vapour compression refrigeration systems, including i. Introduce historical aspects of various artificial refrigeration methods, namely: a. Use of ice transported from colder regions (Section 1.2) Use of ice harvested in winter and stored in ice houses (Section 1.2) Use of ice produced by nocturnal cooling (Section 1.2.1) Use of evaporative cooling (Section 1.2.2) Cooling by salt solutions (Section 1.2.3)ģ. Introduce aspects of various natural refrigeration methods, namely: a. Define refrigeration and air conditioning (Section 1.1) 2. $W =\dfrac) \times 58.2 = 1.7625 \times 1.2 \times 58.2 = 123.Objectives of the lesson: The objectives of this lesson are to: 1. Since the relative humidity is 50%, the vapour pressure of water in air (p$_v$) is:
Find the humidity ratio, dew point temperature and enthalpy of moist air on this day.Īt 37$^o$C the saturation pressure (p$_s$) of water vapour is obtained from steam tables as 6.2795 kPa. On a particular day the weather forecast states that the dry bulb temperature is 37$^o$C, while the relative humidity is 50% and the barometric pressure is 101.325 kPa.