It makes use of a certain thermal property that varies with temperature. 4.1 Transfer of thermal energy: Thermal energy is always transferring from a place with high temperature to a place with low temperature. So we can say that the direction of the thermal energy transferring is from warmer place to a colder one. The main ways for transfer of thermal energy are: • conduction • convection • radiation Conduction: When we have a direct contact between at least two objects with a different temperature. The warmer objects transfer energy to the colder object and because of that it occurs: the temperature of the colder object became to rise when at the same time the temperature of the warmer object became to decrease.
Name Matthew Scott Lau Index No. 20 Class 4.11 Stephen 1 Introduction Global Warming is the average rise of temperature across the globe and it is increasing at an alarming rate due to harmful emissions to the atmosphere. One major contributor which holds a great Global Warming Potential (GWP) is the activity of refrigerants, such as chlorofluorocarbons (CFCs). Refrigerants are used to artificially induce a low temperature in an enclosed area for the comfort of it’s user(s). The constant use of such refrigerants will eventually lead to an increase in average global temperature, encouraging further use for refrigerants - the source of the problem.
However, a desiccant cooling system is not efficient in removing sensible heat from the air. And hence, desiccant systems are often used in combination with direct or indirect evaporative cooling system, vapour compression refrigeration system or vapour absorption system to remove latent and sensible heat of the process air. (desiccant cooling systems) Isothermal and adiabatic (type of adiabatic) In a simple desiccant cycle, the desiccant solution absorbs the moisture from the air. This phenomenon is exothermic. Desiccant being liquid, absorbs the heat of absorption.
Furthermore, it has a great influence on the number of theoretical stages needed for the separation and the diameter of the column. Firstly, operating pressure affects the temperatures of heating and cooling. The bubble point and dew point temperatures of a mixture of a given composition depend strongly on pressure. For mixtures in which the vapor phase behaves as an ideal gas and the liquid phase behaves as an ideal liquid solution, Raoult’s law can be used, together with a suitable vapor-pressure model, to predict the pressure temperature relationships. For less ideally behaved mixtures, other fluid property models, including cubic equations of state and activity co-efficient models, are needed.
On the other hand, air conditioning systems used chemicals that are integral to the system and air from the surroundings. These two also differ in the circulation in their system. Refrigeration systems keep the low temperature of atmosphere in a unit. This is attained with the help of the compressors where the cool air is drawn to reuse the gas. While air conditioning systems release the air to cool a space or room with the fan in the unit.
In this experiment the envionrmental gradient is temperature taken at a certain altitude and distance from the wall. The temperature is affected by the sunlight that the area or its surroundings are receiving. The surroundings is the distance from the wall of the building as well as the canopy cover. The temperature is also affected by other environmental factors such as the speed of the wind because that would cool the area down as well as how much of the area is shaded. Hypothesis: I predict that
Thermogravimetric Analysis (TGA) measures the physical and chemical properties as a function of increasing temperature or time in a controlled atmosphere. TGA analysis is used in determination of the composition of materials and thermal stability at temperatures up to 1200°C. This technique can characterize materials which exhibit weight loss or gain due to decomposition, oxidation, or dehydration. There are three types of Thermogravimetry namely 1. Static or isothermal Thermogravimetry 2.
The heat from the water stream transferred to the air stream raises the air's temperature and its moisture content to 100%, and this air is discharged to the atmosphere. Evaporative heat rejection equipments such as cooling towers are commonly used to provide significantly lower water temperatures than what can be achieved by air cooled or dry heat rejection devices, like a car radiator, thereby achieving more cost-effective and energy efficient process of cooling. An example of evaporative cooling can be personified when something hot is rapidly cooled by putting water on it, which evaporates, cooling rapidly. The cooling potential of a wet surface is much better than a dry one. Wet type cooling tower is considered as the most
Human thermal comfort is usually affected by the temperature of the air [3,4,6], relative humidity [3,4,5,6], wind speed [3,4] and solar radiation . This review aims to firstly, discuss the factors that affect a microclimate and how it improves thermal comfort. This paper will also introduce about the urban heat island (UHI) effect and suggest ways to control the microclimate to remove the UHI effect and enhance thermal comfort. Factors affecting microclimate and how they affect thermal comfort The microclimate in an urban area can be affected by factors like tree canopy covers and wind speed . Tree canopy covers cause a decrease in energy penetration through the soil, as the canopies absorb and reflect away the solar radiation .