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Vapor and Advanced Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The ideal working fluid used in the combined ORC for waste heat recovery systems (WHRS) should have the following features: The working fluid should be cheaply available so that it can lower the cost of WHRS.The working fluid should have low boiling point and latent heat of evaporation so as to recover waste heat from low-temperature source, in particular coolant heat.The working fluid should have low critical temperature, critical pressure, and high thermal conductivity.The working fluid should have stable physical and chemical properties and thermal stability.The working fluid should be nontoxic, nonflammable, nonexplosive, and environmental friendly.
Introduction
Published in Sotirios Karellas, Tryfon C. Roumpedakis, Nikolaos Tzouganatos, Konstantinos Braimakis, Solar Cooling Technologies, 2018
Sotirios Karellas, Tryfon C. Roumpedakis, Nikolaos Tzouganatos, Konstantinos Braimakis
Refrigerant is defined as the working fluid that is used to produce the cooling effect of a refrigeration system. On the other hand, the fluid that is cooled down by the refrigeration system is referred to as the cooling medium of the refrigeration cycle.
Gas–Liquid Two-Phase Flows
Published in Greg F. Naterer, Advanced Heat Transfer, 2018
Desirable characteristics of the working fluid include a high latent heat of vaporization, high thermal conductivity, high surface tension, low dynamic viscosity, and suitable saturation temperature. Also, the working fluid should effectively wet the wick material. Examples of effective working fluids include water or ammonia for operation at moderate temperatures, or liquid metals, such as sodium, lithium, or potassium, at high temperatures (above 600°C). A heat pipe with water as the working fluid and a wick vessel material of copper–nickel can provide a surface heat flux exceeding 146 W/cm2 at temperatures of about 200°C. Typical heat flux values of common heat pipes, working fluids, and wick vessels, are listed in Table 5.3.
Numerical investigation of solar flat plate collector using different working fluids
Published in International Journal of Ambient Energy, 2023
Pragya Narayana Prasad, Sarita Kalla
A study of the prior literature is quite essential before presenting the current study. Some of the first few works related to CFD analysis of SPFC using different working fluids other than air and water can be dated back to 2014. Karami et al. tested the collector efficiency using a suspension of single-walled carbon nanohorns in water (Karami, Raisee, and Delfani 2014). Other fluids such as CuO-water, multiwalled carbon nanotubes-water, Al2O3-water, TiO2-water, and SiO2-water nanofluids have also been numerically investigated as working fluids in SFPCs (Rangababu, Kiran Kumar, and Srinivasa Rao 2015; Ekramian, Etemad, and Haghshenasfard 2014; Maouassi et al. 2018; Mahian et al. 2014; Mirzaei and Mohiabadi 2021). However, water and air are the most commonly used working fluids in real-life situations. Unar et al. 2020 compared the performance of a single tube SFPC with water and air as the working fluids using ANSYS FLUENT 14.0 model (Unar et al. 2020).
Experimental analysis of wet gas-liquid water mixture within the tank of water in glass evacuated tube solar water heater
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Yunze Shen, Jin-Yuan Qian, Zhilin Sun
It is obvious that there are most literatures on the evacuated solar tubes, operating conditions, and the design of the passive vacuum tube solar water heaters. Besides, several investigations have been conducted on the nanofluid as working fluid. It can be concluded that no research has been implemented applying wet gas-liquid water mixture as the working fluid inside the water tank of passive vacuum tube solar water heater. Thus, the main objective of this work is to analyze the thermal performance and thermal stratification of passive vacuum tube solar water heater at different proportions of wet gas-liquid water mixture. The novelty of this work is evaluating the effect of different proportions of wet gas-liquid water mixture on the thermal performance and thermal stratification of passive vacuum tube solar water heater, and develop a correlation for thermal efficiency through different proportions of mixture. Five water outlet locations of water storage tank were used to produce the wet gas-liquid water mixtures with five different proportions inside water storage tank. Thus, the effects of wet gas-liquid water mixture proportions on the thermal performance are studied.
Modeling of vertical ground heat exchangers
Published in International Journal of Green Energy, 2021
Seama Koohi-Fayegh, Marc A. Rosen
Heat pumps use the same mechanical principles as refrigerators. While refrigerators remove heat from the interior and discharge it to the environment, heat pumps take heat from the environment and concentrate it to heat the building in the summer. A heat pump is a machine that transfers heat from a source to another region by employing a refrigeration cycle. Although heat normally flows from higher to lower temperatures, a heat pump reverses that flow and acts as a “pump” to move the heat. Therefore, a heat pump can be used both for space heating in the winter and for cooling (air conditioning) in the summer. In the refrigeration cycle, a refrigerant (known as the “working fluid”) is compressed (as a liquid) then expanded (as a vapor) to absorb and remove heat. The heat pump transfers heat to a space to be heated during the winter period and, by reversing the operation, extracts (absorbs) heat from the same space to be cooled during the summer period.