Energy Coefficient Of Performance Research Articles

PERFORMANCE OF HEAT PUMP BASED ON COMPOSITE ADSORBENT ‘SILICA GEL – CRYSTALLINE HYDRATE’

Performance of an adsorptive heat pump has been studied. The factors affecting the efficiency of its work have been analyzed. Operating parameters and efficiency of adsorptive heat pumps and adsorptive heat storage devices have been compared. An algorithm of calculating the basic operating characteristics of an adsorption heat pump in heat supply systems has been proposed. It involves calculating the mass transfer coefficient, final absolute humidity of the air flow passed though adsorbent layer, the water uptake or adsorption and the useful heat of adsorption and heat of condensation, determination of heat inputs for the operation of the device such as heating the adsorbent, case of the device, hydraulic circuit, the water in the tank and adsorbed water, heat of desorption and heat of evaporation, estimation the coefficient of energy performance. The evaluation criteria of the efficiency of adsorptive heat pumps and heat storage devices have been compared. It is shown that the operating parameters of the adsorptive heat pump and the adsorptive thermal energy storage device based on composite adsorbents ‘silica gel – sodium sulfate’ and ‘silica gel – sodium acetate’ are the same, i.e. airflow rate 0.08 - 0.1 m3/s and initial absolute humidity of airflow 0.03 – 0.04 kg/m3, which are corresponded with maximal efficiency of the device. The temperature of the humid air flow directed to the adsorbent layer is suggested to be set at 20 – 40 °C. The measures to increase the efficiency of the adsorptive heat pump are proposed. It is shown that ultrasonic air humidification allows to increase the coefficient of energy performance by almost 2 times compared to steam humidification. The obtained results can be used for developing energy-efficient heating systems of residential premises.

Drivers to allow widespread adoption of ATES systems: a reflection on 40 years experience in The Netherlands

Drivers to allow widespread adoption of ATES systems: a reflection on 40 years experience in The Netherlands

Thermodynamic investigation of solar-powered integrated humidification-dehumidification and vapor compression refrigeration system

Throughout the functioning of an air conditioner working on the principle of vapor compression (VCR system), the heat which is taken up by its evaporator, is thrown away by its condenser. The heat rejected by the condenser is frequently wasted, and it actually causes thermal pollution by increasing the temperature of the surrounding air. Aside from this, freshwater shortage is a severe issue in many regions. With the use of the waste heat of VCR system, it is intended to combine the air conditioning and humidification-dehumidification (HDH) water desalination, and to address these problems. The system supplies potable water, cool air, and warm water whilst avoiding the thermal pollution. Though the integration of the cooling and the desalination units has attracted the interest of some scholars, the duct construction in the current work is the new idea. In this study, the required spray water temperature in humidifier is found considering the human comfort inside the cabin. The impacts of ambient conditions, temperature of saline water, and efficiency of the humidifier on output and performance parameters are explored. The thermodynamic model developed in this research is validated by experimental studies. For the provided operating conditions, the gained output ratio (GOR), the cooling performance (CP), the energy performance coefficient (COEP), and the exergetic efficiency are 2.26, 0.70, 1.94, and 18.67%, respectively.

Effect of design assumptions on the performance evaluation of zero energy housing

Renovation projects in social housing tend to focus on diminishing the costs of the renovation. An affordable solution is sought for an average household, thus assumptions are made about the residents’ behaviour when calculating the energy performance of the dwellings. However, households have different needs and preferences, and therefore the actual use of the building can affect the achievement of the zero energy goals. In the Netherlands, until 2020, the calculation of the energy performance coefficient (EPC) was necessary to obtain building permission. The EPC was calculated based on standardised occupancy, and took into account the characteristics of the building envelope and installations. Furthermore, the EPV (energieprestatievergoeding, energy performance compensation in English) is an instrument used by housing associations and landlords to recover part of their investments in renovating social housing into (nearly) zero energy homes through a regulated increase in the rent, while protecting the residents from increase on their costs of living. In this research, we used a monitoring case study in the Netherlands to investigate the effect of assumptions made during design regarding occupants’ behaviour, preferences, needs and lifestyle on achieving energy neutrality goals. The following questions are answered: What assumptions where made during the design of the building, and how do they differ from actual behaviour?, and what are the consequences of the behaviour for the performance of the building and for the EPV? The objective of this research is to determine the importance of design assumptions in the design and evaluation of zero energy buildings.

Performance analysis of solar-powered integrated desalination and air conditioning system

ABSTRACT During the operation of the vapor compression refrigeration (VCR) cycle, heat is absorbed in the evaporator and rejected from the condenser to the environment. The heat rejected by the condenser is often wasted, and it raises the ambient air temperature, resulting in thermal pollution. Apart from that, freshwater scarcity is a severe concern in many areas. An integrated system of humidification-dehumidification (HDH) desalination and air conditioning using waste heat from the VCR system is proposed to address these difficulties. The system provides freshwater, cooled air, and hot water while preventing thermal pollution. Although the combination of desalination and cooling systems has piqued the attention of a few researchers, the duct architecture used in this work is a first. The study determines an appropriate humidifier spray water temperature based on human comfort conditions. It investigates the effects of ambient temperature and relative humidity, saline water temperature, and humidifier efficiency on output and performance metrics. The experimental studies are used to validate the thermodynamic model established in this paper. From one cubic meter of air, 31.50 kJ of heat and 40.53 mL of freshwater are extracted using 0.66 kW of power. The cooling performance (CP), gained output ratio (GOR), coefficient of energy performance (COEP), and exergy efficiency for the given operating parameters are 1.34, 4.29, 1.72, and 13.99%, respectively. The cost of freshwater production is $ 0.010076 per liter.

Multi-objective capacity optimization of a distributed energy system considering economy, environment and energy

With the climate change and depletion of fossil energy, distributed energy systems (DESs) have attracted widespread attention. In this study, a DES driven by solar, geothermal, aerothermal, natural gas and power grid is constructed with energy conversion devices modeled based on part load performance. A novel operation strategy for the DES is presented considering the complementary characteristics of different energy sources. Besides, a multi-objective nonlinear optimization model for the device capacity is proposed with economic, environmental and energy objectives considered simultaneously. To solve the optimization model, an integrated solution method combining Non-dominated Sorting Genetic Algorithm-II, Technique for Order Preference by Similarity to an Ideal Solution and Shannon entropy approach is developed. A case study of an indoor swimming pool in Changsha city of China is undertaken. Optimal equipment capacity and corresponding energy management strategies of the case are obtained. The final number and capacity of air source heat pump (ASHP) are determined via improving its part load ratio. Additionally, three schemes are set to investigate the effects of constant efficiency/COP of energy conversion devices and operation strategies on the capacity optimization of DESs. Results indicate that constant efficiency/COP of equipment yields an 11.7% drop in annual total cost (ATC), a 10.4% increment in annual total CO2 emission (ATE) and a 12.5% reduction in coefficient of energy performance (CEP). ATC and ATE of the optimal solution acquired under a conventional operation strategy increase by 6.8% and 3.7%, while CEP decreases by 66.9%. This work provides a guidance for the future application of DESs.

Comparative thermodynamic performance assessment of two-stage cycle for various refrigerants

In this paper, the thermodynamic performance evaluations of the two-stage cooling cycle are investigated comparatively for different refrigerants under the same operating conditions. Due to their environmentally friendly properties, CO2, R600, R600a, R161, and R134a are selected as the refrigerants. The change in energy performance coefficient (COPen) and exergy performance coefficient (COPex) of the defined cycle are investigated according to the various indicators, such as reference temperature, gas cooler outlet temperature and pressure. Results are shown that, at the evaporator temperature of −5°C and the gas cooler outlet temperature of 40°C, the COPen of the cooling cycle are 1.644, 1.603, 1.452, 2.0356 and 1.928 for the refrigerants CO2, R600, R600a, R161 and R134a, respectively. Furthermore, COPex of the cycle are computed as 25.94%, 15.57%, 14.07%, 19.73% and 18.68% for the same refrigerants in the same order. In addition, the overall exergy destruction rate of the cooling cycle for CO2 refrigerant is calculated as 145.69 kW.

Comparative Thermodynamic Performance Assessment of Two-Stage Cycle for Various Refrigerants

In this paper, the thermodynamic performance evaluations of the two-stage cooling cycle are investigated comparatively for different refrigerants under the same operating conditions. Due to their environmentally friendly properties, CO2, R600, R600a, R161, and R134a are selected as the refrigerants. The change in energy performance coefficient (COPen) and exergy performance coefficient (COPex) of the defined cycle are investigated according to the various indicators, such as reference temperature, gas cooler outlet temperature and pressure. Results are shown that, at the evaporator temperature of −5°C and the gas cooler outlet temperature of 40°C, the COPen of the cooling cycle are 1.644, 1.603, 1.452, 2.0356 and 1.928 for the refrigerants CO2, R600, R600a, R161 and R134a, respectively. Furthermore, COPex of the cycle are computed as 25.94%, 15.57%, 14.07%, 19.73% and 18.68% for the same refrigerants in the same order. In addition, the overall exergy destruction rate of the cooling cycle for CO2 refrigerant is calculated as 145.69 kW.

Performance of the Adsorptive Solar Refrigerators Based on Composite Adsobents ’Silica Gel – Sodium Sulphate’

The performance of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sodium sulphate’ is studied. An optimum composition of adsorbent ’silica gel – sodium sulphate’ is suggested to be of 20 % silica gel and 80 % sodium sulphate. The basic factors affected the net coefficient of energy performance of the adsorptive solar refrigerator were stated. Net coefficients of performance of solar adsorptive refrigerator based on composite ‘silica gel – sodium sulphate’ are stated to change from 0.25 to 0.34 during operating period. Utilization of the adsorption heat is suggested to warm the heat carrier which applied to heat adsorbent during regeneration.

High effective heterogeneous plasma vortex reactor for production of heat energy and hydrogen

This work is a continuation of our previous studies [1-10] of physical parameters and properties of a long-lived heterogeneous plasmoid (plasma formation with erosive nanoclusters) created by combined discharge in a high-speed swirl flow. Here interaction of metal nanoclusters with hydrogen atoms is studied in a plasma vortex reactor (PVR) with argon-water steam mixture. Metal nanoclusters were created by nickel cathode’s erosion at combined discharge on. Dissociated hydrogen atoms and ions were obtained in water steam by electric discharge. These hydrogen atoms and ions interacted with metal nanoclusters, which resulted in the creation of a stable plasmoid in a swirl gas flow. This plasmoid has been found to create intensive soft X-ray radiation. Plasma parameters of this plasmoid were measured by optical spectroscopy method. It has been obtained that there is a high non-equilibrium plasmoid: Te > TV >> TR. The measured coefficient of energy performance of this plasmoid is about COP = 2÷10. This extra power release in plasmoid is supposed to be connected with internal excited electrons. The obtained experimental results have proved our suggestion.

Energy conservation benefit of water-side free cooling in a liquid desiccant and evaporative cooling-assisted 100% outdoor air system

The main purpose of this research was to experimentally investigate a liquid desiccant and evaporative cooling-assisted 100% outdoor air system. The proposed system was integrated with water-side free cooling in the desiccant solution and process air cooling to enhance its energy performance. The experimental results show that the required cooling water temperature for the desiccant solution is higher than the conventional cooling water supply temperature; that is, approximately 22–27°C. Consequently, water-side free cooling was applied to produce the cooling water for the desiccant solution. The operation of the proposed system with the water-side economizer showed a 40–70% effectiveness of the indirect evaporative cooler, while that of the direct evaporative cooler was greater than 95%, and the supply air temperature ranged between 17 and 20°C. The energy coefficient of performance (COP) of water-side free cooling applied to cool the desiccant solution was 8–17, whereas that of the conventional air-cooled chiller was 1–3. Economic consideration indicated that the operating energy savings might offset the penalty in the initial cost of the proposed system.

Influence of carbon/nitrogen ratio and non-aerated zone size on performance and energy efficiency of a partially-aerated submerged fixed-film bioreactor

Performance and energy efficiency of an upflow partially aerated submerged fixed-film (UP/ASFF) bioreactor was evaluated during a 10-month operation period. Increasing loading rates at constant HRT and COD/N increased nitrogen removals. Increase of non-aerated zone could also improve the nitrogen removals up to 83%. Energy performance coefficient based on required electrical energy showed that the energy efficiency of the system increases at lower COD/N value and bigger non-aerated zone for simultaneous COD and nitrogen removal from the synthetic wastewater. The present study showed also similar performance for municipal wastewater, demonstrating the potential of UP/ASFF system to treat high-ammonium municipal wastewaters.

The effect of energy performance regulations on energy consumption

Governments have developed energy performance regulations in order to lower energy consumption in the housing stock. Most of these regulations are based on the thermal quality of the buildings. In the Netherlands, the energy efficiency for new buildings is expressed as the EPC (energy performance coefficient). Studies have indicated that energy regulations are successful in lowering the energy consumption in residential buildings. However, the actual energy consumption is usually different from the expected energy consumption. This paper explores the effectiveness of energy performance regulations in lowering the energy consumption of dwellings built in the Netherlands after 1996. The effect of the EPC and thermal characteristics on energy consumption was determined by statistical analyses of data on actual energy consumption. The results showed that energy reductions are seen in dwellings built after the introduction of energy performance regulations. However, results suggest that to effectively reduce energy consumption, the tightening of the EPC in not enough. Policies aimed at controlling the construction quality and changing occupant behaviour are also necessary to achieve further energy reductions.

Towards Energy-neutral New Housing Developments. Municipal Climate Governance in The Netherlands

The Dutch government intends to sharpen the current energy performance standard of the national building regulations for new buildings (Energy Performance Coefficient) step by step to an energy-neutral level by 2020. In their climate policies, municipalities are preparing to meet this level for new buildings—some of them even earlier. Nevertheless, possibilities to impose energy performance levels, higher than formulated at national level, are limited for municipalities. This paper investigates, how and through which policy instruments Dutch municipal authorities can promote energy-neutral new housing developments. This research suggests the following municipal climate governance approach and instruments: (1) an integrated design strategy for sustainable energy systems throughout the city: in both urban areas and buildings; (2) market-party-selection in tendering procedures based on sustainability criteria, including the energy performance of dwellings; (3) encouragement of community engagement for the deployment of renewable energy sources; (4) (inter)regional cooperation among cities in similar climatic zones on the development of both more uniform calculation methods for zero-energy buildings, and of a more uniform methodology for cities to monitor progress towards the self-set targets. However, stable and long-term-oriented European and national financial support for municipalities seems to be needed for municipal climate governance to become successful.