scholarly journals Installation and Operation of a Solar Cooling and Heating System Incorporated with Air-Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 996 ◽  
Author(s):  
Li Huang ◽  
Rongyue Zheng ◽  
Udo Piontek
Keyword(s):  
Heating System ◽  
Cooling Capacity ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Energy Yield ◽  
Absorption Chiller ◽  
Annual Average ◽  
Water Storage Tank ◽  
Solar Cooling

A solar cooling and heating system incorporated with two air-source heat pumps was installed in Ningbo City, China and has been operating since 2018. It is composed of 40 evacuated tube modules with a total aperture area of 120 m2, a single-stage and LiBr–water-based absorption chiller with a cooling capacity of 35 kW, a cooling tower, a hot water storage tank, a buffer tank, and two air-source heat pumps, each with a rated cooling capacity of 23.8 kW and heating capacity of 33 kW as the auxiliary system. This paper presents the operational results and performance evaluation of the system during the summer cooling and winter heatingperiod, as well as on a typical summer day in 2018. It was found that the collector field yield and cooling energy yield increased by more than 40% when the solar cooling and heating system is incorporated with heat pumps. The annual average collector efficiency was 44% for cooling and 42% for heating, and the average coefficient of performance (COP) of the absorption chiller ranged between 0.68 and 0.76. The annual average solar fraction reached 56.6% for cooling and 62.5% for heating respectively. The yearly electricity savings accounted for 41.1% of the total electricity consumption for building cooling and heating.

Design and Modeling of One Refrigeration Ton Solar Assisted Adsorption Air Conditioning System

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
M. Alkhair ◽  
M. Y. Sulaiman ◽  
K. Sopian ◽  
C. H. Lim ◽  
E. Salleh ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Hot Water ◽  
Activated Carbon Fiber ◽  
Coefficient Of Performance ◽  
Weather Data ◽  
Adsorption System ◽  
Water Storage Tank ◽  
Chilled Water

The modeling of the performance of a one refrigeration ton (RT) solar assisted adsorption air-conditioning refrigeration system using activated carbon fiber/ethanol as the adsorbent/adsorbate pair has been undertaken in this study. The effects of hot water, cooling water, chilled water inlet temperatures, and hot water and chilled water flow rates were taken into consideration in the optimization of the system and in the design of the condenser, evaporator, and hot water storage tank. The study includes analysis of the weather data and its effect on both the adsorption system and the cooling load. This is then followed by estimation of the cooling capacity and coefficient of performance (COP) of the adsorption system as a function of the input parameters. The results of the model will be compared to experimental data in a next step.

Experiment Based Performance Analysis of a Solar Absorption Cooling and Heating System in Carnegie Mellon University

2008 ◽  
Author(s):  
Ming Qu ◽  
David H. Archer ◽  
Hongxi Yin
Keyword(s):  
Residential Buildings ◽  
Heating System ◽  
Test System ◽  
Hot Water ◽  
Small Scale ◽  
Absorption Chiller ◽  
Solar Absorption ◽  
Solar Cooling ◽  
Absorption Cooling ◽  
Solar Absorption Cooling

The center for building performance and diagnostic (CBPD) at Carnegie Mellon University has successfully designed, installed and tested a solar cooling and heating system to assess the feasibility of solar cooling for small scale commercial buildings or residential buildings with aspects of technology and energy efficiency. This solar cooling and heating system is primarily comprised of parabolic trough solar collectors, PTSC’s and a 16 kW dual energy source double effect (2E) absorption chiller. The 2E absorption chiller driven by PTSCs was tested to produce chilled water or hot water throughout a number of clear days in summer and winter. The analyses of the experimental data defined the system performance: the efficiency of the solar collector, the capacity and COP of the chiller, and the heat transfer coefficient of the heat recovery exchanger, by using a statistical approach, based on the energy balance equation. In the solar cooling tests during July 2007 in Pittsburgh, PA, the average efficiency of PTSCs was 35% when they were operated at about 155°C for driving the 2E absorption chiller and the chiller was able to provide 8 to 14 kW cooling with COP in the range 1.0 to 1.2; the overall system efficiency is in the range 0.35 to 0.41. In the near future, this solar absorption cooling and heating test system and its operation will be integrated with the cooling, heating and ventilation units for long term utilization.

scholarly journals Design of a 35 kW Solar Cooling Demonstration Facility for a Hotel in Spain

2020 ◽  
Vol 10 (2) ◽  
pp. 496 ◽  
Author(s):  
Pedro J. Martínez ◽  
Pedro Martínez ◽  
Victor M. Soto ◽  
Luis A. Bujedo ◽  
Juan Rodriguez
Keyword(s):  
Cooling System ◽  
Cooling Capacity ◽  
Point Of View ◽  
Hot Water ◽  
Design Decision ◽  
Specific Storage ◽  
Economic Point ◽  
Water Storage Tank ◽  
Solar Cooling ◽  
The Hours

Solar cooling systems have the advantage of the coincidence between the hours of cooling demand and the hours of solar radiation availability, and they can contribute to reduce the energy consumption in buildings. However, the high cost of thermal solar cooling facilities with absorption chillers, maintenance issues, legionella risk and water consumption (associated to the necessary cooling tower) have limited the use of these systems to demonstration projects. A simplified Transient System Simulation Tool (TRNSYS) model was developed to provide the owner of the demonstration facility the information he needs for design decision-making. This model was validated with experimental data registered in a solar cooling system designed and built by the authors. Different collector field surfaces, hot water storage tank volumes, and absorption machine driving temperatures were analyzed for a hotel demonstration facility. In terms of the energy delivered to the absorption chiller the optimum dimensioning corresponded to the lowest values of the driving temperature (75 °C) and specific storage volume (15 Lm2). From an economic point of view, the saving of 1515 euros per year when compared with an electric compression chiller does not compensate the investment of 3000 euros per kW of cooling capacity that cost the thermal solar cooling facility.

A Dynamic Model of a Single-Stage LiBr-H2O Absorption Chiller

2016 ◽  
Author(s):  
Prangtip Samutr ◽  
Ali Al Alili
Keyword(s):  
Water Temperature ◽  
Dynamic Model ◽  
Cooling Capacity ◽  
Hot Water ◽  
Single Stage ◽  
Coefficient Of Performance ◽  
Maximum Relative Error ◽  
Outlet Temperature ◽  
Absorption Chiller ◽  
Chilled Water

This paper presents a dynamic model of a single-stage LiBr-H2O absorption chiller. A numerical model has been developed based on mass and energy balance equations and heat transfer equations. The model is developed using MATLAB program and the system of non-linear ordinary differential equation is solved using the 4th-order Runge-Kutta method. The model is validated with experimental results from pertained literature. The results show that the maximum relative error is found when comparing the dynamic model predicted chilled water outlet temperature to experimental data, which is around 9%. The effect of the inlet hot water temperature on the hot, cooling and chilled water outlet temperatures, cooling capacity and coefficient of performance (COP) are also studied. The results show that as the hot water outlet temperature increases, the outlet temperatures of cooling and chilled water slightly change. Moreover, the cooling capacity increases and the COP slight decreases as the hot water temperature increases.

Efficient and Flexible Tri-Generation With Two-Stage Absorption Chiller

2006 ◽  
Author(s):  
S. Plura ◽  
C. Kren ◽  
C. Schweigler
Keyword(s):  
Double Effect ◽  
Cooling Capacity ◽  
Significant Loss ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Coupling Scheme ◽  
Exhaust Gas ◽  
Absorption Chiller ◽  
Two Stage ◽  
Heating And Cooling

Aiming for the European and North American tri-generation market, highly-efficient systems are being developed. At the moment, single-stage absorption chillers are typically coupled to co-generation engines through a single hot water loop at temperatures below 100°C (210°F). In this configuration, the heat from the exhaust gas at temperatures of about 400-500°C (750-930°F) is transferred to the water loop, which is accompanied by a significant loss of exergy. A substantial increase in system performance can be achieved by a stepwise utilisation of the exhaust gas enthalpy in a Double-Effect and a Single-Effect cycle. In this combination of one-and two-stage chillers the coefficient of performance (COP) increases from about 0.7 to almost 1.0 whereby the cooling capacity rises by about 25%. In order to facilitate optimum adaptation of the aggregates - i.e. motor engine and absorption chiller - and to give maximum flexibility an innovative system concept has been developed. The new coupling scheme is based on a standard direct-fired Double-Effect chiller and introduces only minor design changes, like adaptation of the thermal layout of the exhaust gas driven regenerator heat exchanger of the chiller. No additional low temperature regenerators are required. In case of simultaneous heating and cooling the system supports a continuous switchover between maximum cooling and maximum heating capacity. In this mode up to 80% of the driving heat for cold production can be recovered as useful heat at temperatures up to 100°C (210°F). A description of the coupling scheme together with a discussion of energetic and operational characteristics of the concept is presented. Full-scale demonstration projects are under preparation.

scholarly journals Factors Shaping A/W Heat Pumps CO₂ Emissions—Evidence from Poland

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1576
Author(s):  
Piotr Jadwiszczak ◽  
Jakub Jurasz ◽  
Bartosz Kaźmierczak ◽  
Elżbieta Niemierka ◽  
Wandong Zheng
Keyword(s):  
Air Quality ◽  
Power System ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Conventional Heating ◽  
Additional Stress ◽  
The European Union ◽  
Energy Mix

Heating and cooling sectors contribute to approximately 50% of energy consumption in the European Union. Considering the fact that heating is mostly based on fossil fuels, it is then evident that its decarbonization is one of the crucial tasks for achieving climate change prevention goals. At the same time, electricity sectors across the globe are undergoing a rapid transformation in order to accommodate the growing capacities of non-dispatchable solar and wind generators. One of the proposed solutions to achieve heating sector decarbonization and non-dispatchable generators power system integration is sector coupling, where heat pumps are perceived as a perfect fit. Air source heat pumps enable a rapid improvement in local air quality by replacing conventional heating sources, but at the same time, they put additional stress on the power system. The emissions associated with heat pump operation are a combination of power system energy mix, weather conditions and heat pump technology. Taking the above into consideration, this paper presents an approach to estimate which of the mentioned factors has the highest impact on heat pump emissions. Due to low air quality during the heating season, undergoing a power system transformation (with a relatively low share of renewables) in a case study located in Poland is considered. The results of the conducted analysis revealed that for a scenario where an air-to-water (A/W) heat pump is supposed to cover space and domestic hot water load, its CO2 emissions are shaped by country-specific energy mix (55.2%), heat pump technology (coefficient of performance) (33.9%) and, to a lesser extent, by changing climate (10.9%). The outcome of this paper can be used by policy makers in designing decarbonization strategies and funding distribution.

scholarly journals A Study on the Performance of a Cascade Heat Pump for Generating Hot Water

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4313 ◽  
Author(s):  
Boahen ◽  
Choi
Keyword(s):  
Heat Exchanger ◽  
Energy Saving ◽  
Heat Pump ◽  
Heat Pumps ◽  
Hot Water ◽  
Research Interest ◽  
Coefficient Of Performance ◽  
Energy Saving Potential ◽  
Heating Capacity

The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.

Simulation and Experimental Analysis of a Solar Driven Absorption Chiller With Partially Wetted Evaporator

2008 ◽  
Author(s):  
Jan Albers ◽  
Giovanni Nurzia ◽  
Felix Ziegler
Keyword(s):  
Cooling System ◽  
Cooling Water ◽  
Hot Water ◽  
Absorption Chiller ◽  
Efficient Operation ◽  
Part Load ◽  
Solar Cooling ◽  
Wetted Area ◽  
Solar Cooling System ◽  
Load Conditions

The efficient operation of a solar cooling system strongly depends on the chiller behaviour under part-load conditions since driving energy and cooling load are never constant. For this reason the performance of a single stage, hot water driven 30 kW H2O/LiBr-absorption chiller employed in a solar cooling system with a field of 350 m2 evacuated tube collectors has been analysed under part-load conditions with both simulations and experiments. A simulation model has been developed for the whole absorption chiller (Type Yazaki WFC-10), where all internal mass and energy balances are solved. The connection to the external heat reservoirs of hot, chilled and cooling water is done by lumped and distributed UA-values for the main heat exchangers. In addition to an analytical evaporator model — which is described in detail — experimental correlations for UA-values have been used for condenser, generator and solution heat exchanger. For the absorber a basic model based on Nusselt theory has been employed. The evaporator model was developed taking into account the distribution of refrigerant on the tube bundle as well as the change in operation from a partially dry to an overflowing evaporator. A linear model is derived to calculate the wetted area. The influence of these effects on cooling capacity and COP is calculated for three different combinations of hot and cooling water temperature. The comparison to experimental data shows a good agreement in the various operational modes of the evaporator. The model is able to predict the transition from partially dry to an overflowing evaporator quite well. The present deviations in the domain with high refrigerant overflow can be attributed to the simple absorber model and the linear wetted area model. Nevertheless the results of this investigation can be used to improve control strategies for new and existing solar cooling systems.

Modeling of a Wellhead Heating Methodology With Heat Pipes in Coal Mines

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Hongyang Zhang ◽  
Kewen Li ◽  
Lipeng Zhao ◽  
Lin Jia ◽  
Mohammed Kaita ◽  
...  
Keyword(s):  
Heat Pipe ◽  
New Technologies ◽  
Low Cost ◽  
Coal Mines ◽  
Heat Pipes ◽  
Heating System ◽  
Heat Pumps ◽  
Hot Water ◽  
Winter Period ◽  
Ground Source Heat Pumps

Abstract Many coal mines are located at the middle and high latitudes. In winter, coal mining facilities may be operated under the freezing conditions. Burning coal for hot water is usually used to heat up the facilities, which is not environmentally friendly and energy efficient. Currently, the ground source heat pumps and other new technologies have been applied for heating in coal mines and have achieved some success. However, the working characteristics and costs of these technologies are not suitable for the antifreeze at the wellhead. Heat pipe technology has the following advantages: automatic operation with the change of atmosphere temperature (AMT) and low cost of construction and maintenance, which can overcome the drawbacks of the aforementioned technologies. In this article, a heating system based on heat pipe technology has been designed and modeled. The system extracts heat from the shallow normal temperature zone (NTZ) to automatically heat the coal wellhead in winter. For the heating system, the effects of AMT, the temperature of NTZ, the frozen zone thickness (FZT), the thermal conductivity, and the heat pipe quantity (HPQ) on the heating performance have been modeled and investigated using comsol multiphysics. The modeling results have been analyzed and discussed. The modeling data showed that the system based on heat pipes could meet the antifreeze requirements for the designed system during the winter period. The wellhead heating system proposed in this article may achieve the purpose of replacing fossil energy with shallow geothermal energy.

Implementation of Solar Thermal Driven Absorption Cooling in the Southeast

2010 ◽  
Author(s):  
Stephen M. Smith
Keyword(s):  
Heating System ◽  
Hot Water ◽  
Solar Thermal ◽  
Absorption Chiller ◽  
Solar Absorption ◽  
Modeling Process ◽  
Annual Behavior ◽  
Cooling Loads ◽  
Radiant Floor Heating ◽  
Floor Heating

A 35,000 ft2 [3,251 m2] Creative Arts instruction building is being constructed on the campus of Haywood Community College in Clyde, NC (∼25 miles [40 km] west of Asheville). The building’s HVAC system consists of a solar absorption chiller, two parallel back-up electric chillers, and radiant floor heating with condensing boiler back-up. Hot water is to be heated by 117 solar thermal panels with thermal energy storage in a 12,000 gallon [45,000 liters] insulated tank and service to both the absorption chiller and the radiant under-floor heating system. Peak cooling loads and unfavorable solar conditions are to be handled by parallel electric chillers, operated in sequence to achieve maximum performance. Emergency radiant under-floor heating hot water back-up is to be handled by gas-fired condensing boilers in the event of unavailable solar heated hot water. This paper will examine the extensive modeling process required of the system as performed in EnergyPlus, how preliminary modeling results influenced the control and design strategy, the annual behavior of the system and the importance of controllability.

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