Desiccant Degradation in Desiccant Cooling Systems: A System Study

1993 ◽  
Vol 115 (4) ◽  
pp. 237-240 ◽  
Author(s):  
A. A. Pesaran
Keyword(s):  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Ventilation Mode ◽  
Worst Case ◽  
Cooling Systems ◽  
Degradation Data ◽  
Percent Loss ◽  
The Impact

We predicted the impact of desiccant degradation on the performance of an open-cycle desiccant cooling system in ventilation mode using the degradation data on silica gel obtained from a previous study. The degradation data were based on thermal cycling desiccant samples and exposing them to ambient or contaminated air. Depending on the degree of desiccant degradation, the decrease in the thermal coefficient of performance (COP) and the cooling capacity of the system for low-temperature regeneration was 10 percent to 35 percent. The 35 percent loss occurred based on the worst-case desiccant degradation scenario. Under more realistic conditions the loss in system performance is expected to be lower.

scholarly journals Impact of internal heat gain profiles on the design cooling capacity of landscaped offices

2021 ◽  
Vol 246 ◽  
pp. 07003
Author(s):  
Seyed Shahabaldin Seyed Salehi ◽  
Andrea Ferrantelli ◽  
Hans Kristjan Aljas ◽  
Jarek Kurnitski ◽  
Martin Thalfeldt
Keyword(s):  
Building Materials ◽  
Cooling System ◽  
Internal Heat ◽  
Cooling Capacity ◽  
Thermal Mass ◽  
Large Set ◽  
Cooling Systems ◽  
Heat Gain ◽  
Depth Analysis ◽  
The Impact

Using passive methods in façade design for controlling heating and cooling needs is an important prerequisite for constructing cost-effective nearly zero-energy buildings. Optimal control of solar heat gains reduces the cooling demand and the size of the active cooling systems. However, applying such methods increases the impact of internal heat gains on the heat balance of the buildings, and accordingly also the dimensions of cooling systems. Therefore, a good model of internal heat gains is needed for a reliable and optimal sizing of the cooling sources. This paper aims to bring understanding to developing internal heat gains models for sizing the cooling systems. For this purpose, several weekly internal heat gain profiles were selected from a large set of tenant-based electricity use measured in 4 office buildings in Tallinn. The selection was based on maximum daily or weekly peak loads of an office space per floor area. The selected profiles and the schedule of EN 16798-1 were used to dimension ideal coolers in the zones of a generic floor model with landscaped offices developed in IDA-ICE 4.8. The model had variable window sizes and thermal mass of the building materials. Finally, the internal heat gains models resulting in the largest cooling capacity were identified. We found that utilizing thermal mass can reduce the cooling system size by up to 7% on average and the models with big windows and light structure need the largest cooling systems. The cooling loads obtained with the profile of EN 16798-1 did not significantly differ from the average of other profiles’ results. This paper focused mainly on the zonal dimensioning of cooling systems, therefore a more in-depth analysis of the different occupancy patterns as well as developing models for dimensioning the cooling system at the building level, is needed.

Experimental Study of Capillary Radiant Cooling System with Parameters Changing

2013 ◽  
Vol 300-301 ◽  
pp. 1048-1053 ◽  
Author(s):  
Yong Hong Wang
Keyword(s):  
Room Temperature ◽  
Cooling System ◽  
Cooling Capacity ◽  
Test Methods ◽  
Radiation Response ◽  
Volume Changes ◽  
Indoor Temperature ◽  
Radiant Cooling ◽  
Radiation Laboratory ◽  
The Impact

In this paper, the test methods of radiation laboratory and data analysis in detail were introduced. The impact of the capillary system with different parameters changing, such as water temperature or water flow the capillary cooling capacity changes, and the capillary cooling system when the initial radiation response time were specificially studied. Under different parameters while cooling capillary volume changes associated with the indoor temperature can be seen under certain conditions, the capillary cooling capacity and room temperature has a linear relationship.

Desiccant Degradation in Desiccant Cooling Systems: An Experimental Study

1993 ◽  
Vol 115 (4) ◽  
pp. 212-219 ◽  
Author(s):  
A. A. Pesaran
Keyword(s):  
Thermal Cycling ◽  
Silica Gel ◽  
Molecular Sieves ◽  
Cooling System ◽  
Ambient Air ◽  
Activated Alumina ◽  
Humid Air ◽  
Cooling Systems ◽  
Degradation Data ◽  
Capacity Loss

We conducted experiments to quantify the effects of thermal cycling and exposure to contamination on solid desiccant materials that may be used in desiccant cooling systems. The source of contamination was cigarette smoke, which is considered one of the worst pollutants in building cooling applications. We exposed five different solid desiccants to “ambient” and “contaminated” humid air: silica gel, activated alumina, activated carbon, molecular sieves, and lithium chloride. We obtained the moisture capacity of samples as a function of exposure time. Compared to virgin desiccant samples, the capacity loss caused by thermal cycling with humid ambient air was 10 percent to 30 percent for all desiccants. The capacity loss because of combined effect of thermal cycling with “smoke-filled” humid air was between 30 percent to 70 percent. The higher losses occurred after four months of experiment time, which is equivalent to four to eight years of field operation. Using a system model and smoke degradation data on silica gel, we predicted that, for low-temperature regeneration, the loss in performance of a ventilation-cycle desiccant cooling system would be between 10 percent to 35 percent, in about eight years, with higher value under worst conditions.

Optimized Refrigerant Flow Rate and Dimensions of the Ejector Employed in a Modified Ejector Vapor Compression System

2020 ◽  
Vol 28 (04) ◽  
pp. 2050038
Author(s):  
Dishant Sharma ◽  
Gulshan Sachdeva ◽  
Dinesh Kumar Saini
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Proposed Model ◽  
Condenser Temperature ◽  
Vapor Compression System ◽  
Vapor Compression Cooling

This paper presents the analysis of a modified vapor compression cooling system which uses an ejector as an expansion device. Expanding refrigerant in an ejector enhances the refrigeration effect and reduces compressor work. Therefore, it yields a better coefficient of performance. Thermodynamic analysis of a constant area ejector model has been done to obtain primary dimensions of the ejector for given condenser and evaporator temperature and cooling capacity. The proposed model has been used to design the ejector for three refrigerants; R134a, R152a and R1234yf. The refrigerant flow rate and the diameters at various sections of the ejector have been obtained by doing numerical modeling in Engineering Equation Solver (EES). Refrigerant R1234yf demanded the highest diameter requirements at a fixed 5∘C evaporator temperature and 40∘C condenser temperature for a given range of cooling load. Both primary and secondary refrigerants flow rates are higher for R1234yf followed by R134a and then R152a.

Experimental Investigation on the Efficiency of a Control Dependent NiTi-Based Cooling Process

2014 ◽  
Author(s):  
Marvin Schmidt ◽  
Andreas Schütze ◽  
Stefan Seelecke
Keyword(s):  
Energy Efficient ◽  
Cooling System ◽  
Experimental Testing ◽  
Control Process ◽  
Process Variations ◽  
Coefficient Of Performance ◽  
Testing System ◽  
Cooling Process ◽  
Commercial Development ◽  
The Impact

Energy efficient systems and environmentally friendly solutions are the focus of many commercial development projects. Current refrigeration technology carries a significant share of global energy consumption and exploring alternative refrigeration principles has become increasingly important. Shape memory alloys (SMA’s), especially Nickel-Titanium (NiTi) alloys, generate a large amount of latent heat during solid-state phase transformations, which can lead to a significant cooling effect in the material. These materials not only provide the potential for an energy efficient cooling process, they also minimize the impact on the environment by reducing the need for conventional ozone-depleting refrigerants. This paper presents the first experimental results obtained in a project within the DFG Priority Programme SPP 1599 “Ferroic Cooling”. It focuses on the performance of a control-dependent process of a NiTi-based cooling system. First, a suitable cooling process is introduced and the underlying mechanisms of the process are explained. Then different process variations are developed, which influence the efficiency of the cooling process. These process variations are systematically analyzed with a novel, experimental testing system capable of tuning process parameters independently. The testing system is able to measure force, displacement, temperature distribution and heat simultaneously. The coefficient of performance (of the cooling process) can then be determined by which the influence of the control process on the efficiency can be observed.

scholarly journals System Design of Solar Absorption Cooling : A Case Study in Building of Engineering Physics Department UGM

KnE Energy ◽  
2015 ◽  
Vol 2 (2) ◽  
pp. 22
Author(s):  
Andang Widiharto ◽  
Didit Setyo Pamuji ◽  
Atik Nurul Laila ◽  
Fiki Rahmatika Salis ◽  
Luthfi Zharif ◽  
...  
Keyword(s):  
Global Warming ◽  
Solar Collector ◽  
Air Conditioning ◽  
Cooling System ◽  
Renewable Energy Sources ◽  
Coefficient Of Performance ◽  
Thermal Coefficient ◽  
Solar Absorption ◽  
Absorption Cooling ◽  
Solar Absorption Cooling

<p>Air conditioning (AC) is one of the most building’s energy consumer, included in building of Engineering Physisc’s Departement, Universitas Gadjah Mada (UGM). The declining of fossil fuel reserves and the increasing effects of global warming, forcing the world to switch to renewable energy sources. This paper discusses the design of solar absorption cooling system to replace conventional AC in seven lecture halls of Engineering Physic’s Departement, UGM. There are some steps that have been done to design the solar absorption cooling, i.e. do a study of the potential availability of solar energy, calculate the cooling loads, analyze the thermodynamic process of the system, determine the type of collector to be used and calculate area of solar collector needed. The thermal coefficient of performance (COP) of the system designed was about 0.84 which could use some types of flat plate solar collector with each area corresponding to each efficiency values. </p><p><strong>Keyword</strong> : Air conditioning; global warming; solar absorption cooling; solar collector</p>

scholarly journals Experimental Study to Performance Improvement of Vapor Compression Cooling System Integrated Direct Evaporative Cooler and Condenser

2018 ◽  
Vol 215 ◽  
pp. 01017
Author(s):  
Arfidian Rachman ◽  
Lisa Nesti
Keyword(s):  
Energy Use ◽  
Cooling System ◽  
Electricity Consumption ◽  
Weather Condition ◽  
Heat Removal ◽  
Cooling Capacity ◽  
Cooling Power ◽  
Cooling Systems ◽  
Evaporative Cooler ◽  
And Performance

For areas with very hot and humid weather condition increased latent and sensible load are a major problem in cooling systems that will increase compressor work so that electricity consumption will also increase. Combined condenser with direct evaporate cooling will increase the heat removal process by using an evaporative cooler effect that will increase the efficiency of energy use. This paper presents the study of the use of evaporator cooling and condenser. This paper mainly calculated energy consumption in steam compression cooling systems and related problems. From the results of this study, the use of condensers with evaporative cooling, power consumption can be reduced to 46% and performance coefficient (COP) can be increased by about 12%, with 1,2 kW cooling capacity.

scholarly journals Innovative Turbine Intake Air Cooling Systems and Their Rational Designing

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6201
Author(s):  
Andrii Radchenko ◽  
Eugeniy Trushliakov ◽  
Krzysztof Kosowski ◽  
Dariusz Mikielewicz ◽  
Mykola Radchenko
Keyword(s):  
Gas Turbines ◽  
Maximum Rate ◽  
Cooling System ◽  
Ambient Air ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Thermal Loads ◽  
Cooling Systems ◽  
Air Cooling System

The efficiency of cooling ambient air at the inlet of gas turbines in temperate climatic conditions was analyzed and reserves for its enhancing through deep cooling were revealed. A method of logical analysis of the actual operation efficiency of turbine intake air cooling systems in real varying environment, supplemented by the simplest numerical simulation was used to synthesize new solutions. As a result, a novel trend in engine intake air cooling to 7 or 10 °C in temperate climatic conditions by two-stage cooling in chillers of combined type, providing an annual fuel saving of practically 50%, surpasses its value gained due to traditional air cooling to about 15 °C in absorption lithium-bromide chiller of a simple cycle, and is proposed. On analyzing the actual efficiency of turbine intake air cooling system, the current changes in thermal loads on the system in response to varying ambient air parameters were taken into account and annual fuel reduction was considered to be a primary criterion, as an example. The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the range beyond the first maximum rate. The rational value of design cooling capacity provides practically the maximum annual fuel saving but with the sizes of cooling systems reduced by 15 to 20% due to the correspondingly reduced design cooling capacity of the systems as compared with their values defined by traditional designing focused to cover current peaked short-term thermal loads. The optimal value of cooling capacity providing the minimum sizes of cooling system is very reasonable for applying the energy saving technologies, for instance, based on the thermal storage with accumulating excessive (not consumed) cooling capacities at lowered current thermal loads to cover the peak loads. The application of developed methodology enables revealing the thermal potential for enhancing the efficiency of any combustion engine (gas turbines and engines, internal combustion engines, etc.).

scholarly journals Simulation of the performance of alternative refrigerants in liquid chillers

2001 ◽  
Vol 215 (4) ◽  
pp. 429-441 ◽  
Author(s):  
I. N. Grace ◽  
S. A. Tassou
Keyword(s):  
Dynamic Models ◽  
Control Strategies ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
System Component ◽  
Alternative Refrigerants ◽  
Expansion Valve ◽  
Shell And Tube Evaporator ◽  
The Impact

The impact of refrigeration systems on the environment can be reduced by (a) the use of alternative refrigerants which are less harmful to the environment and (b) the optimization of systems and control strategies to deliver increased levels of energy efficiency. Mathematical modelling offers the opportunity to test the performance of systems under different operating conditions and with alternative refrigerants. Dynamic models allow comparison of both transient and steady state behaviour and this is of particular importance for liquid chillers since these systems can operate under transient conditions for long periods. This paper covers the development of a general dynamic model for the simulation of liquid chillers. Brief descriptions of the system component models are given, including a semihermetic reciprocating compressor and thermostatic expansion valve as well as a shell-and-tube evaporator and condenser. The paper demonstrates the application of the model to simulate the performance of a liquid chiller retrofitted with a range of alternative refrigerants. The performance of the system is determined in terms of cooling capacity, power consumption and coefficient of performance for a range of different operating conditions. The relative performance of each refrigerant is discussed and the preferred alternative identified for typical applications.

Numerical Analysis of Heat and Mass Transfer in an Annular Porous Adsorber for Solar Cooling System

2010 ◽  
Vol 297-301 ◽  
pp. 802-807
Author(s):  
Nadia Allouache ◽  
Rachid Bennacer ◽  
Salahs Chikh ◽  
A. Al Mers
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
System Performance ◽  
Technology Development ◽  
Cooling System ◽  
Coefficient Of Performance ◽  
Cooling Systems ◽  
Solar Cooling ◽  
Adsorbed Quantity ◽  
Solar Cooling System

The present study deals with a solid adsorption refrigerator analysis using activated carbon/methanol pair. It is a contribution to technology development of solar cooling systems. The main objective consists to analyse the heat and mass transfer in an annular porous adsorber that is the most important component of the system. The porous medium is contained in the annular space and the adsorber is heated by solar energy. A general model equation is used for modelling the transient heat and mass transfer. Effects of the key parameters on the adsorbed quantity, the coefficient of performance, and thus on the system performance are analysed and discussed.

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