Experimental Study on LiNO3-NH3 Diffusion-Absorption Refrigeration System

2011 ◽  
Vol 474-476 ◽  
pp. 2335-2340 ◽  
Author(s):  
Han Dong Wang
Keyword(s):  
Solar Energy ◽  
Heat Source ◽  
Air Conditioning ◽  
Waste Heat ◽  
Absorption Refrigeration ◽  
Source Temperature ◽  
Industry Waste ◽  
Heat Source Temperature ◽  
Refrigeration Capacity ◽  
Diffusion Absorption

In order to utilize solar energy and industry waste heat to reduce electricity consumption in heating, ventilating, air conditioning and refrigerating (HVAC&R) engineering, the authors developed a new style diffusion-absorption refrigeration (DAR) system. It can be driven by heat sources with low temperature, and in which LiNO3-NH3-He is used as working fluids and a spray absorber with a solution cooler is designed to enhance the mass and heat transfer, respectively. What presented here is about the modified experiment set and the latest experiment results. The experiments show that the system can start to operate when the temperature of heat source (hot water) reaches to 60°C and it can meet the temperature requirement of air conditioning when heat source temperature varies in the range of 70～83°C. The evaporating temperature varies from 10～-13°C at various absorbing temperatures when heat source temperature reaches the level of 83～95°C. The corresponding refrigeration capacity and coefficient of performance (COP) varies in the range of 1.90～4.22kW and 0.177～0.332, respectively. It is also found that the evaporating temperature, refrigeration capacity and COP are so sensitive to absorbing temperature rather than generating or condensing temperature that the absorbing temperature can be used to regulate the working condition and parameters of the DAR system, e.g. by means of modulating the flow rate of cooling water circulating in the solution cooler equipped to the spray absorber. Thus, in the fields with plenty of solar energy or industry waste heat, the new style DAR system can be considered as an ideal candidate for utilizing low-grade energy, saving energy and reducing emission.

scholarly journals Parametric Study of a Supercritical CO2 Power Cycle for Waste Heat Recovery with Variation in Cold Temperature and Heat Source Temperature

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6648
Author(s):  
Young-Min Kim ◽  
Young-Duk Lee ◽  
Kook-Young Ahn
Keyword(s):  
Heat Source ◽  
Thermal Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Low Pressure ◽  
Power Cycle ◽  
Cooling Temperature ◽  
Source Temperature ◽  
Heat Source Temperature

The supercritical carbon dioxide (S-CO2) power cycle is a promising development for waste heat recovery (WHR) due to its high efficiency despite its simplicity and compactness compared with a steam bottoming cycle. A simple recuperated S-CO2 power cycle cannot fully utilize the waste heat due to the trade-off between the heat recovery and thermal efficiency of the cycle. A split cycle in which the working fluid is preheated by the recuperator and the heat source separately can be used to maximize the power output from a given waste heat source. In this study, the operating conditions of split S-CO2 power cycles for waste heat recovery from a gas turbine and an engine were studied to accommodate the temperature variation of the heat sink and the waste heat source. The results show that it is vital to increase the low pressure of the cycle along with a corresponding increase in the cooling temperature to maintain the low-compression work near the critical point. The net power decreases by 6 to 9% for every 5 °C rise in the cooling temperature from 20 to 50 °C due to the decrease in heat recovery and thermal efficiency of the cycle. The effect of the heat-source temperature on the optimal low-pressure side was negligible, and the optimal high pressure of the cycle increased with an increase in the heat-source temperature. As the heat-source temperature increased in steps of 50 °C from 300 to 400 °C, the system efficiency increased by approximately 2% (absolute efficiency), and the net power significantly increased by 30 to 40%.

Analysis of novel regenerative thermo-mechanical refrigeration system integrated with isobaric engine

2020 ◽  
pp. 1-27
Author(s):  
Ahmad K. Sleiti ◽  
Wahib Al-Ammari ◽  
Mohammed Al-Khawaja
Keyword(s):  
Heat Source ◽  
Environmental Effects ◽  
Power Efficiency ◽  
Waste Heat ◽  
Working Fluid ◽  
Refrigeration System ◽  
Cooling Systems ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature

Abstract Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.

Performance Evaluation of Solar Energy Driven Diffusion Absorption Refrigeration Cycle Using Inorganic Fluid Pair

2018 ◽  
Vol 26 (04) ◽  
pp. 1850031 ◽  
Author(s):  
Kishan Pal Singh ◽  
Onkar Singh
Keyword(s):  
Computer Simulation ◽  
Performance Evaluation ◽  
Solar Energy ◽  
Thermodynamic Modeling ◽  
Air Conditioning ◽  
Ammonia Concentration ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Simulation Based ◽  
Diffusion Absorption

In the present era, the refrigeration and air conditioning have become essential requirements, and consume significant portion of energy available. The refrigeration requirements are severe in the hot and humid countries and, the refrigeration systems based upon solar energy are desirable. This study focuses on the thermodynamic modelling of ammonia water diffusion absorption refrigeration cycle with helium as pressure equalizing gas. The performance of the cycle is investigated parametrically by computer simulation based on thermodynamic modeling. It is found that the performance shows a loss of 37.36% at 110[Formula: see text]C while only 23.52% at 140[Formula: see text]C a generator temperature in the range of 120 to 150[Formula: see text]C is best suited for ammonia concentration range of 0.25–0.45 to get optimum performance.

scholarly journals Lumped Element Model for Thermomagnetic Generators Based on Magnetic SMA Films

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1234
Author(s):  
Joel Joseph ◽  
Makoto Ohtsuka ◽  
Hiroyuki Miki ◽  
Manfred Kohl
Keyword(s):  
Heat Source ◽  
Waste Heat ◽  
Dynamic Properties ◽  
Element Model ◽  
Magnetic Shape Memory ◽  
Time Resolved ◽  
Source Temperature ◽  
Lumped Element ◽  
Heat Source Temperature ◽  
Lumped Element Model

This paper presents a lumped element model (LEM) to describe the coupled dynamic properties of thermomagnetic generators (TMGs) based on magnetic shape memory alloy (MSMA) films. The TMG generators make use of the concept of resonant self-actuation of a freely movable cantilever, caused by a large abrupt temperature-dependent change of magnetization and rapid heat transfer inherent to the MSMA films. The LEM is validated for the case of a Ni-Mn-Ga film with Curie temperature TC of 375 K. For a heat source temperature of 443 K, the maximum power generated is 3.1 µW corresponding to a power density with respect to the active material’s volume of 80 mW/cm3. Corresponding LEM simulations allow for a detailed study of the time-resolved temperature change of the MSMA film, the change of magnetic field at the position of the film and of the corresponding film magnetization. Resonant self-actuation is observed at 114 Hz, while rapid temperature changes of about 10 K occur within 1 ms during mechanical contact between heat source and Ni-Mn-Ga film. The LEM is used to estimate the effect of decreasing TC on the lower limit of heat source temperature in order to predict possible routes towards waste heat recovery near room temperature.

scholarly journals The Effect of Thermal Conductance of Evaporator on Performance of a Two Stage Adsorption Chiller (Reheat) with Different Mass Allocation

2015 ◽  
Vol 62 (2) ◽  
pp. 133-139
Author(s):  
T Sultana ◽  
MZI Khan
Keyword(s):  
Heat Source ◽  
Waste Heat ◽  
Thermal Conductance ◽  
Cycle Performance ◽  
Distinct Advantage ◽  
Two Stage ◽  
Adsorption Chiller ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Mass Allocation

Now a days, adsorption heat pumps receive considerable attention as they are energy savers and environmentally benign. Silica gel/water based adsorption cycles have a distinct advantage in their ability to be driven by heat of near-ambient temperature so that waste heat below 100 °C can be recovered. One interesting feature of refrigeration cycles driven by waste heat is that they do not use primary energy as driving source. In the present paper, an analytic investigation of a two-stage adsorption refrigeration chiller using re-heat with different mass allocation was performed to determine the influence of the thermal conductance of evaporator as well as the heat source temperature on the chiller performance. Result shows that cycle performance is strongly influenced by large thermal conductance values of the evaporator. Besides it is observed that the chilled water outlet has lower value for comparatively higher value of heat source temperature. DOI: http://dx.doi.org/10.3329/dujs.v62i2.21978 Dhaka Univ. J. Sci. 62(2): 133-139, 2014 (July)

scholarly journals Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

2011 ◽  
Vol 32 (3) ◽  
pp. 57-70 ◽  
Author(s):  
Dariusz Mikielewicz ◽  
Jarosław Mikielewicz
Keyword(s):  
Power Plant ◽  
Low Temperature ◽  
Heat Source ◽  
Silicone Oil ◽  
Hot Water ◽  
Working Fluid ◽  
Preliminary Heating ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Steam Heat

Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Sign in / Sign up

Export Citation Format

Share Document