Heat Pumps

Cool roofs represent an acknowledged, relatively simple, and low-cost strategy to reduce cooling energy demand of buildings and mitigate urban heat island phenomena. The purpose of this paper is to study the coupled passive-active effect produced by such a technology, where the active effect consists of the cool roof capability to decrease the suction air temperature of heat pump external units, when these units are located over the roof. This "cooling" benefit produces an extra increase of the energy performance of the heat pump in cooling mode, given that it produces the decrease of the temperature lift between the source and the output. In order to study this twofold effect, an industrial building with an office area located in Rome, Italy, was continuously monitored in summer 2012. The main results showed that the cool roof allows to decrease the roof overheating up to 20°C. The office indoor air temperature also decreased, even if the same set-point temperature was kept constant during the whole campaign. The energy requirement for cooling decreased by about 34%. In order to investigate the "active" contribution, suction air temperature was monitored and a new simple analytical model is proposed in order to estimate the cool roof active effect.

Gegenstand der hier vorliegenden Arbeit ist die Untersuchung der Kombination von Wärmepumpen mit einer thermischen Solaranlage für den häuslichen Wärmebedarf. Die Untersuchung wurde in Form von Simulationen verschiedener Anlagenvarianten durchgeführt und hatte das Ziel die Systeme unter energetischen, wirtschaftlichen und ökologischen Kriterien zu analysieren. Die Arbeit soll einen Einstieg in das Thema ermöglichen und eine Einschätzung liefern, ob und wenn ja wann eine Kombination dieser beiden Technologien sinnvoll erscheint.

Given the need for decarbonization of the heating sector and the acute need of a propane replacement in the U.S. Upper Midwest, this study quantifies the techno-economic characteristics of sustainable heating electrification in isolated rural, residential buildings in cold climates without natural gas supply. Archetypal buildings are modeled under four levels of electrification. At each electrification level, a parametric solar photovoltaic (PV) sizing analysis is performed and the total life cycle cost, renewable fraction and greenhouse gas (GHG) emissions are calculated based on the primary energy supply for each building type. Cost optimal solutions are stress-tested with multi-dimensional sensitivity analyses. The results show that the total life cycle cost favors heating electrification in all cases and combining PV with heat pumps can reduce residential building GHG emissions by up to 50% immediately. This effect will grow over time, with over 90% reduction of building emissions if renewable energy targets are met. In using primary energy and emissions along with the multi-dimensional sensitivities, this study unique demonstrates the complex techno-economic interactions of PV and heat pumps. It is concluded that electrification is an economically viable decarbonization method for cold climates both now and in the future.

This article presents a newly designed and realized system for heat recovery from waste water. The waste water is the heat source, the temperature of which is about 44-49 o C. The heat recovery process is performed using a plate heat exchanger and two heat pumps. The mentioned components are serially linked. The heat sink is clean water which is pumped from a 40 meter deep well and is heated up from 13-14 o C to 50-55 o C. Waste water is cooled down from 44-49 o C to 13-14 o C. The mass flow rate of the clean and waste water is approximately the same. This heat recovery process reaches a significant coefficient of performance (COP) with 6.03-6.5 meaning that 83-85% of the energy demand for heating clean water is provided by the recovery processand electric energy is consumed only for 17-15%. From the aspect of energy efficiency: the plate heat exchanger participates by about 49%, the low temperature heat pump by 30%, the high temperature heat pump by 21% in the heat recovery.

• Effects of wind on the thermo-flow characteristics of cooling towers have been revealed. • Windbreaker types have been studied to decrease the negative effects of wind. • Results show that it is possible to use the momentum effect of wind. • Movable windbreakers should be used to change the direction according to the wind. A B S T R A C T Performance of natural draft dry cooling towers is significantly affected when the wind velocity is higher than a critical level according to their design and geometry. During this type of conditions, global electricity generation of power plants using especially dry type cooling towers is substantially reduced, up to as high as 40%. In order to decrease the reduction in electricity generation of power plants, it is possible to study on the dimensions of the cooling towers. Additionally, using different types of windbreakers can reduce the effects of unfavorable operating conditions. However, the direction of the wind changes with the seasons although the prevailing wind direction is nearly the same. In this study, internal flat and combination of internal flat–external rounded windbreakers have been analyzed by using the computational fluid dynamics approach. The combination of windbreakers, which is able to move axially around the cooling tower, has been propounded to arrange the flow characteristics during the windy days. The studies on the windbreakers in the literature have been aimed to decrease the negative effects of the wind; however, the design in this study provides also an increase in the air mass flowrate due to the momentum effect of the wind.

Heat pump is environmentally friendly, have high performance and low running cost, despite these advantages heat pumps do not have wide usage.  One of the important disadvantages of heat pumps their high prices. In comparison with conventional systems, their prices are high. Furthermore, the lack of enough public reliability to heat pump
is another factor in spreading wide areas. Because these systems are not mature like the conventional systems problems can be seen more frequently. In this quick written draft, some common problems and precautions are given. Your comments are very welcome.

This study investigates the use of air source heat pumps (ASHPs) in detached residential homes in cold climates. The study aims to assess if ASHPs can provide reliable heating responses in mild, cold, and very cold climate zones across Canada. Moreover, it investigates how the use of ASHPs in a warming climate will affect the energy use intensity (EUI) and greenhouse gas (GHG) emission compared to the current most-commonly adopted gas furnaces. Different systems are compared under current and future climate scenarios. Findings indicated that ASHP systems would be best suited for residential use in Vancouver (zone 5A) across different scenarios (present 1998-2014, near future 2030-2041, and far future 2056-2075) due to the milder temperatures annually. Reversely, the colder climates of Toronto and Quebec City may require supplementing sizing of the heating systems and would result in lower efficiency and high GHG due to the higher emission factors of non-electrical power demand.

This work presents an experimental investigation of the performance of a HDH system operated by heat pump. The novel heat pump system provides the necessary heating for the humidifier and cooling for the dehumidifier of the HDH system. The proposed integrated unit is capable of producing freshwater as well as cooling effect for space conditioning through water heated or cooled heat exchange units. Influence of various operating parameters such as feed water flowrate, feed water temperature and chilled water flowrate on the general assessment metrics, including gain output ratio (GOR), recovery ratio (RR), coefficient of performance (COP), energy utilization factor (EUF), Specific electrical energy consumption (SEEC) and productivity are evaluated. The cost of freshwater production from the proposed desalination unit is estimated. Results showed that the integrated system is capable of attaining maximum GOR of 4.07, RR of 4.86%, COP of 4.85, EUF of 3.04, and productivity of 287.8 L/day. The minimum SEEC of the system was found to be 160.16 kWhr per cubic meter of freshwater. The system is also capable of providing cooling load of 3.07 kW while producing the needed desalinated water.

Space cooling energy consumption is a significant component of building energy consumption, and in recent years it has attracted much attention worldwide owing to its significantly increasing usage. The variable refrigerant flow (VRF) system is one common type of cooling equipment for buildings in China and is applied extensively to residential and office buildings. The performance of VRF systems significantly influences the cooling energy consumption of buildings. The system energy efficiency and electricity consumption are the main indicators employed to evaluate the performance of VRF systems. It is hard to obtain the actual energy efficiency and electricity consumption of VRF systems in buildings because of the high cost of the required complicated measurements. This study proposes a virtual sensor modeling method to determine the actual energy efficiency and electricity consumption of 344 VRF systems in residential buildings. Statistical and clustering analyses are conducted to determine the energy efficiency and electricity consumption to obtain distributions and typical operation load patterns of VRF systems in residential buildings in China. The main findings are as follows: the main range of the Seasonal Energy Efficiency Ratio (SEER) for the cooling season is from 2.9 to 4.4; the median SEER in the Hot Summer and Cold Winter zone is lower than in another climate zones; the longer cooling duration may lead to greater electricity consumption, and the electricity load for VRF systems electricity load is periodic for each day. The oversizing issue is common for VRF systems in the dataset, which also led to the lower energy efficiency of VRF systems. The high usage of VRF systems appeared from July 27th to August 26th. The findings provide recommendations for designing VRF systems in residential buildings. Keywords variable refrigerant flow (VRF), energy efficiency, virtual sensor, residential building Article History

"In order to characterise the performance of domestic air and ground source heat pumps (ASHP and GSHP), the Coefficient of Performance (COP) from over 100 models was collected, along with the temperature rise across the heat pump.

From the relationship between COP and temperature rise, the annual seasonal performance in the UK was estimated. COPs for ASHP and GSHP operating in the UK are calculated, with output temperatures ranging from 30 to 60°C. These are compared to published results from independent tests and field trials."

Heat pumps are a promising technology for heating (and cooling) domestic buildings that provide exceptionally high efficiencies compared with fossil fuel combustion. There are in the region of a billion heat pumps in use world-wide, but despite their maturity they are a relatively new technology to many regions. This article gives an overview of the state-of-the-art technologies and the practical issues faced when installing and operating them. It focuses on the performance obtained in real-world operation, surveying the published efficiency figures for hundreds of air source and ground source heat pumps (ASHP and GSHP), and presenting a method to relate these to results from recent UK and German field trials. It also covers commercial aspects of the technologies, the typical savings in primary energy usage, carbon dioxide emissions abatement that can be realised, and wider implications of their uptake.

4 sharing only not 4 sale Source: Torrent

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Pompa merupakan suatu alat mekanik yang digunakan untuk memindahkan fluida dari suatu tempat menuju tempat lain dengan cara meningkatkan tekanan fluida tersebut. Peningkatan tekanan tersebut digunakan untuk mengatasi hambatan-hambatan pada proses pengaliran berupa: perbedaan tekanan, perbedaan ketinggian, dan hambatan gesek permukaan pompa. Pada sebuah PLTU keberadaan pompa bersifat sangat penting dikarenakan pompa memiliki fungsi untuk mengalirkan fluida kerja yang akan digunakan dalam menghasilkan uap, contoh penggunaannya berupa: boiler feed water pump dan condensate extraction pump. Dalam pemilihan pompa diperlukan beberapa data yang merupakan parameter awal sebelum menentukan pilihan dan jenis pompa yang dipergunakan. Data yang diperlukan adalah debit aliran atau kapasitas produksi, temperature fluida kerja, tekanan fluida kerja, densitas, kecepatan aliran fluida di dalam pipa dan lain-lain.
Selanjutnya adalah data yang berupa hasil perhitungan, di antaranya adalah perhitungan friction loss pipa, kehilangan tekanan (pressure drop) dalam pipa dan fitting, panjang pipa, NPSHA, head total pompa, serta efisiensi pompa.

Humidification-dehumidification is a carrier gas based thermal technique that is ideal for small-scale water desalination applications. One advantage of humidification-dehumidification systems is the ability to utilize low grade and renewable energies as heat source to drive the system. This work presents theoretical investigation of humidification-dehumidification desalination system operated by a heat pump. The model is based on the first law of thermodynamics, describing heat and mass transfer in the combined humidification-dehumidification-heat pump cycle. The model predicts the performance of closed-air open-water water-heated, and modified air-heated cycle coupled with a heat pump. To improve the Gain output ratio and energy recovery of the system, a heat pump is used as the source of heating and cooling for the humidification-dehumidification desalination system. Energy rejected in the condenser is used as a source of heat in the humidifier whereas the cooling effect of the evaporator is used to cool incoming seawater for effective condensation of humid air in the dehumidifier. A parametric study is conducted to investigate the influence of system operating parameters, including water and air flowrate, seawater temperature, and refrigerant flow rate on the system performance. Results indicate a maximum Gain output ratio of 8.88 and 7.63 obtained at 80% components effectiveness and mass flow rate ratio of 0.63 and 1.3 for modified air heated and water heated cycle, respectively. A maximum gain output ratio greater than 10 can be achieved for humidifier and dehumidifier effectiveness of 100% leading to more energy efficient systems. The cost of desalinated water production is calculated and the effect of major parameters on its variation is also presented.

Combination of solar thermal collectors and heat pumps in a single solar assisted heat pump (SAHP) system has been widely used for various purposes including water heating. International Energy Agency, Task 44 of the Solar Heating and Cooling (SHC) Programme, has been working on methods towards most effective use of solar heat pump systems for residential use. The current work aims at reviewing the past and present work conducted on the SAHP systems for low temperature water heating applications. The review approach is based on a visualisation scheme to systematically represent and classify concepts of SAHP systems. Specifically, the key performance data from a number of studies are highlighted and various configurations are compared in order to gain accurate and deep intuitive understanding of SAHP systems. The review faithfully states that having a variety of configurations, parameters and performance criteria may lead to a major inconsistency that increase the degree of complexity to compare and analyse the studies of different systems.

Siklus Carnot merupakan suatu siklus termodinamika yang melibatkan proses isotermal, isobarik, dan isokorik. Siklus ini adalah suatu rangkaian sedemikian rupa sehingga akhirnya kembali kepada keadaan semula. Sistem menjalani proses isotermal dari keadaan A sampai B, kemudian menjalani proses isobarik untuk mengubah sistem dari keadaan B ke keadaan C. Akhirnya proses isokorik membuat sistem kembali ke keadaan awalnya yaitu A. Proses dari A ke keadaan B, kemudian ke keadaan C, dan akhirnya kembali ke keadaan A, menyatakan suatu siklus.

ÖZET Jeotermal ısı pompaları (JIP'ları) olarak da bilinen toprak (yer) kaynaklı ısı pompaları (TKIP veya YKIP), geleneksel ısıtma ve soğutma sistemleriyle karşılaştırıldığı zaman, enerji kullanım verimlerinin daha yüksek olması nedeniyle, binaların ısıtılması ve soğutulması için, uzun yıllardır gelişmiş ülkelerde yaygın olarak kullanılmaktadır. Bunun yanı sıra, 1977 yılından beri Türk piyasasında da kullanılmakta olup, son zamanlarda kullanımı artmaktadır. Bu çalışmada, öncelikle, TKIP' larının çalışma şekli, sistemleri, yararları, sakıncaları, uygulamaları ve dünya çapındaki konumu verilmektedir. Daha sonra, toprak ısı değiştiricisi üzerine yoğunlaşarak, bir TKIP sisteminin güneş enerjisi ile kombinasyonu ve asfalt ısıtılması-soğutulması konusu sunulmaktadır. Anahtar Kelimeler: Toprak kaynaklı ısı pompası, jeotermal ısı pompası, ısı pompası, toprak ısı değiştiricisi, güneş enerjisi, asfalt ısıtılması soğutulması.

This article investigates how hydrofluorocarbon (HFC) refrigerant affects compressor operating conditions and system performance using experimental testing under different conditions. In a heat pump or refrigerator cycle, it is necessary to move the fluid in the system to achieve heating or cooling. The compressor is the responsible component in fluid movement and so is a key factor in system power consumption. For this reason, it is essential to discover ways to increase compressor energy efficiency. R404a refrigerant was selected to evaluate the influence of refrigerant on compressor performance. Compressor inlet and discharge temperatures and pressures were measured experimentally. For the tested refrigerant, compressibility factor (Z) and deviation from ideal gas behavior were analyzed cautiously to compute power consumption, isentropic work, coefficient of performance, energy and exergy state, and compressor efficiency. Also analyzed were the influence of condenser water flow rate and the effect of evaporator inlet temperature. The study discussed here provided results that can be used to enhance the performance of compressors in heating/cooling systems.

Fuel cells are a promising technology for combined heat and power (CHP); however their efficiency and carbon benefits are often overlooked because of their reliance on fossil fuels. This paper sets out the numerical methods and evidence of real-world performance needed to compare fuel cells with other low-carbon technologies. It is demonstrated that firstly, the efficiency of present-day fuel cells is high enough to outperform the best electric heat pumps, even when these are powered exclusively by the best modern power stations. The equivalent COP (coefficient of performance) of today’s fuel cells ranges from 5 to ∞, compared to 3–4 for the best ground source heat pumps. Secondly, this high efficiency means that even when fuelled with natural gas, the heat from a fuel cell is zero- or even negative-carbon when electricity from central power stations is displaced.

Moisture content of food material is a key factor influencing the quality of storage and extending the quality of a food product. Manufacturers develop new technologies to process sensitive food materials to supply new products with improved properties and high quality. The process in which the air is cooled sensibly while the moisture is removed from food is called cooling with dehumidification process. The system fundamentally acts as a heat pump, which pumps the heat from the dehumidified air to a different air stream in another area, with the aid of a refrigerant gas to carry the heat. This article reviews the potential of low-temperature heat pump dehumidifier drying used in the food industry. Moreover, this describes the principle of cooling with dehumidification (CWD) process, the importance of studying psychrometric charts to understand CWD process, measures used in identify energy efficiency, comparison of this method over common dryers, applications, advantages and limitations of the CWD drying method. Practical applications Multiple measures have been taken to increase the drying efficiency of convection drying, especially by the application of cooling with dehumidified techniques. This drying technique has comparably higher energy efficiency, better and consistent product quality and the ability to control drying temperature and humidity over other conventional methods. Low-temperature heat pump dryers are used increasingly applications in the food industry for the drying of grains, fruits, vegetables, herbs, spices, fish, meat, pet foods, and other heat-sensitive food products in several countries.

Global increase in energy demand and fossil fuel prices loaded ever-increasing pressure on identifying and implementing new means to utilise clean and efficient energy resources. Due to the environmental benefits, technical and economic possibilities of Solar-Assisted Heat Pump Systems, there has been a growing interest for such hybrid systems with a variety of system configurations for various climates. International Energy Agency Task 44 of the Solar Heating and Cooling Programme has recently started working on finding methods to most effectively use solar heat pump systems for residential use. In the present study, a novel solar thermal roof collector was developed by primarily exploiting components and techniques widely available on the market and coupled with a commercial heat pump unit. The proposed indirect series Solar-assisted Heat Pump system was experimentally tested and system performance was investigated. Yet, the analysis based on indoor and outdoor testing predominantly focuses on the solar thermal roof collector. A detailed thermal model was developed to describe the system operation. Also, a computer model was set up by using Engineering Equation Solver to carry out the numerical computations of the governing equations. Analyses show that the difference in water temperature could reach up to 18°C while maximum thermal efficiency found to be 26%. Data processing of the series covering the test period represents that Coefficient Performance of the heat pump (COP HP ) and overall system (COP SYS ) averages were attained as COP HP = 3.01 and COP SYS = 2.29, respectively. An economic analysis points a minimum payback period of about three years for the system.

Abstract - This article investigates the energy-economic
optimum of thermal insulation thickness for external wall.
The investigation was performed by applying the method
'total cost '. An appropriate steady-state mathematical
model was developed. The mathematical model consists of
energy and economic part. The economic part of the
model contains algebraic equations for investment and
exploitation. The considered wall was made of brick and
covered with polystyrene as thermal insulation material.
The energy-economic optimum was obtained by applying
an analytical-numerical and graph-numerical method.
The optimization criterion was the minimum of total cost.
The numerical results obtained by the simulation are
presented graphically. The optimum thickness of the
thermal insulation layer is shown in the diagrams. In
addition, by applying the developed mathematical model
and mathematical methods the optimum thickness of
thermal insulation layer was obtained for energy economic
conditions in Serbia in 2015.

Heat Pumps are becoming one of the most considered mechanical conditioning equipment in our buildings. While they are popular, there appears to be quite a vast range of system types and applications in building conditioning. This paper primarily reviews the literature on heat pumps, the various types, and the consideration of design end uses. The fact that there are different energy sources for heat pumps is considered, as well as the different sinks in which energy is stored or dissipated. It is evident that advanced heat pump systems cater well to the use of renewable energy resources. Therefore, in the move towards net-zero energy building operation, the correct selection of a heat pump can help to increase self-consumption of solar PV generation and even make use of direct solar energy heating. This paper reviews the technologies for heat pump selection, application, and design for residential buildings.

Thermal-based renewable and low-grade energy sources to operate humidification-dehumidification (HDH) desalination systems are critically reviewed. The investigated renewable energy sources are solar energy and geothermal energy. The low-grade energy sources such as the waste heat of photovoltaic thermal (PV/T) panels, refrigeration and heat pump systems, and power plants are also investigated. For each hybrid HDH with another driving system, the details of HDH construction, performance, hybridization method, and general observations are summarized and compared in tabular forms. Most of the studies focused on using solar energy and refrigeration and heat pump systems to drive HDH systems. The best performance indices (i.e., gained output ratio (GOR), freshwater production, and freshwater cost) can be obtained by the integration of HDH systems with power plants and then by geothermal energy, especially when a large quantity of freshwater is needed (>200 kg/ h). Refrigeration systems and solar collectors can lead to higher GOR, medium water production, and higher cost. The application of PV/T results in the lowest water production. Despite the high performance of HDH driven by power plants and vapor-compression refrigeration systems, geothermal energy, solar collectors, and PV/T panels could be the right choices for hybridization with HDH systems in off-grid regions.

Solar photovoltaic (PV) technology is now a profitable method to decarbonize the grid, but if catastrophic climate change is to be avoided, emissions from transportation and heating must also decarbonize. One approach to renewable heating is leveraging improvements in PV with heat pumps (HPs). To determine the potential for PV+HP systems in northern areas of North America, this study performs numerical simulations and economic analysis using the same loads and climate, but with local electricity and natural gas rates for Sault Ste. Marie, in both Canada and U.S. Ground-mounted, fixed-tilt, grid-tied PV systems are sized to match 100% of electric loads considering cases both with and without air source HPs for residences with natural gas-based heating. For the first time the results show North American residents can profitably install residential PV+HP systems, earning up to 1.9% return in the U.S. and 2.7% in Canada, to provide for all of their electric and heating needs. Returns on PV-only systems are higher, up to 4.3%; however, the PV capacities are less than half. These results suggest northern homeowners have a clear and simple method to reduce their greenhouse gas emissions by making an investment that offers a higher internal rate of return than savings accounts, CDs and GICs in both countries. Residential PV and solar-powered heat pumps can be considered 25-year investments in financial security and environmental sustainability.

The aim of this article is to present the reason and the process of creating new modified mathematical
model of heat pump plate condenser. The fundamental mathematical model is modified according to
analytical optimization procedure. The adaptation is carried out by applying the procedure of elimination.
The modified mathematical model include 2 governing equations instead of 6. The two governing
equations contain 2 unknown dependent variables and 6 known parameters. The modified mathematical
model is validated using the comparative method. The compared data are obtained by numerical
simulation using fundamental and modified mathematical models. Applying both models the obtained
data fully coincided. By using the new modified mathematical model and implementing the optimization
process may lead to the determination of the maximum energy efficiency of hot water subsystem. The
subsystem comprises a condenser, a circulation pump, a connecting pipeline and the heating units. The
objective function in the optimization process is the coefficient of performance, COP, as a function of the
mass flow rate of the hot water or of the circulation pump power. The paper offers the implementation of
modeling the circulation pump power to achieve the maximum value of the COP.

Geothermal energy has the potential to provide long-term, secure base-load energy and greenhouse gas (GHG) emissions reductions. Climate change is not expected to have any major impacts on the effectiveness of geothermal energy utilization, but the widespread deployment of geothermal energy could play a meaningful role in mitigating climate change and accessible geothermal energy from the Earth's interior supplies heat for direct use and to generate electric energy. The paper deals with the use of geothermal resources for the production of electricity next are technologies of change geothermal energy into electrical energy, future of geothermal energy and advantage and disadvantage of geothermal energy

The main aim of this study is to conduct energetic and exergetic investigations of a dual stage heat pump for drying applications in order to evaluate the performance of the overall system. The integrated system consists of two processes, namely a drying unit and a dual stage heat pump. In the heat pump process, R-134A is used as the thermodynamic fluid and the drying unit is used to reduce the moisture content of the air. There are two evaporators used in the dual stage heat pump process: the first evaporator works at high pressures and the second evaporator works at lower pressures. The second evaporator provides supplementary cooling and drying effect for the air used in the drying unit. In the integrated system, there are two sub-coolers which provide additional heating to R-134A after the condenser. In this study, the energy and exergy efficiencies and exergy destruction rates of the overall integrated system, and each component and subprocess are calculated and discussed in detail. Exergetic performance of each component and subprocess are further investigated to identify where the highest exergy destructions occur in order to minimize irreversibilities within the integrated system and hence enhance the overall exergetic efficiency of the integrated system. The impact of environmental conditions on exergetic efficiency and exergy destruction is investigated via parametric studies. In addition, coefficient of performance (COP) of the whole system and the effect of operating conditions are examined. The highest energy and exergy efficiencies occur when the drying unit’s inlet air mass flow rate is 0.5 kg/s and the environmental pressure and temperature are at 101 kPa and 298K which are 62% and 35%, respectively. The overall integrated system has a COP of around 3.8.

This article compares climate impacts of two heat-pump systems for domestic heating, that is, energy consumption for space heating of a residential building. Using a life cycle approach, the study compared the energy use and greenhouse gas (GHG) emissions of direct electric heating, a conventional air-source heat pump, and a novel ground-source air heat pump innovated by a citizen user, to assess whether such user innovation holds benefit. The energy use of the heat pumps was modeled at six temperature intervals based on duration curves of outdoor temperature. Additionally, two heat pump end-of-life scenarios were analyzed. Probabilistic uncertainty analysis was applied using a Monte Carlo simulation. The results indicated that, in ideal conditions, that is, assuming perfect air mixing, the conventional air-source heat pump’s emissions were over 40% lower and the ground-air heat pump’s emissions over 70% lower than in the case of direct electric heating. Although proper handling of the refrigerant is important, total leakage from the retirement of the heat-pump appliance would increase GHG emissions by just 10%. According to the sensitivity analysis, the most influential input parameters are the emission factor related to electricity and the amount of electricity used for heating.

A steady state simulation model has been developed to evaluate the system performance of a transcritical carbon dioxide heat pump for simultaneous heating and cooling. The simulated results are found to be in reasonable agreement with experimental results reported in the literature. Such a system is suitable, for example, in dairy plants where simultaneous cooling at 4 8C and heating at 73 8C are required. The optimal COP was found to be a function of the compressor speed, the coolant inlet temperature to the evaporator and inlet temperature of the fluid to be heated in the gas cooler and compressor discharge pressure. An optimizing study for the best allocation of the fixed total heat exchanger inventory between the evaporator and the gas cooler based on the heat exchanger area has been carried out. Effect of heat transfer in the heat exchangers on system performance has been presented as well. Finally, a novel nomogram has been developed and it is expected to offer useful guidelines for system design and its optimisation. q Elimination des cristaux de givre sur une plaque froide: effets des fréquences stationnaires et de balayage des champs électriques

This article presents experimental and theoretical investigations of a new configuration of an open-air open-water (OAOW), water-heated (WH), humidification-dehumidification (HDH) desalination system coupled with a vapor compression heat pump (HP) that considers two possibilities of energy recovery. Three different HDH system configurations including the basic system HDH-HP (without brine energy recovery), system A (basic system with brine energy recovery for pre-heating saline water), and system B (basic system with brine energy recovery for pre-heating ambient air) are presented. The performance of the basic system is examined experimentally; while that of systems A and B are assessed theoretically. Furthermore, the theoretical analysis is extended to the basis system to address the boundaries, constraints and limitations of experimental equipment, by analyzing the system performance at extended operation conditions. Results reveal that the developed model shows a good agreement against the experimental findings. Results also show that systems A and B portrayed superior performance over the basic system (especially system A), due to the energy recovery from the rejected brine. A maximum GOR of 2.72, RR of 2.56%, water productivity of 9.23 kg/h and a minimum freshwater cost of 15.14$/m3 are attained experimentally, while theoretical results for system A revealed a maximum GOR of 5.06, RR of 3.98%, water productivity of 11.46 kg/h, and a minimum price of freshwater of 12.38$/m3.

For clarify main affecting factors on air-source transcritical CO 2 heat pump water heaters, and the influence extent of these main affecting factors, at fixed water inlet temperature of 12 C, an experimental research was conducted on a prototype in a range of ambient temperatures (À15 Ce35 C) and water outlet temperatures (55 Ce80 C). Based on the experimental results, effect of water outlet temperatures and ambient temperatures on the optimal discharge pressure and system COP was illustrated, and with change of water outlet temperatures and ambient temperatures, variation of CO 2 gas cooler outlet temperatures, evaporating temperatures and other cycle variables was presented and interpreted. According established simulation model, we conducted simulation for the prototype and the cycle respectively adopted another two gas coolers with difference heat transfer surface. As one conclusion, for an established plant, correlation for the optimal discharge pressure as the function of ambient temperatures and water outlet temperatures can be achieved by fitting numerous simulation or experimental results.

All Lennox product is set up with a systematic coding system for both model numbers and serial numbers. Unit model number (including any dash numbers) and serial number must always be used when referring a problem to Lennox in regard to repair parts, literature, wiring diagrams, etc. Use of proper unit identification numbers and serial numbers will greatly help in expediting any material required for these products.

This paper presents a vapor compression heat pump-driven humidification–dehumidification process with energy recovery option. Two systems with different applications of recovered energy are proposed. System A recovers energy for preheating inlet feed water to the heat pump condenser, while system B recovers energy for preheating the humidifier inlet air. The system performance metrics such as gained output ratio (GOR), recovery ratio (RR), productivity, specific electrical energy consumption (SEEC) and the cost of freshwater production are investigated based on variations in mass flowrate ratios, humidifier effectiveness, seawater temperature, brine heat exchanger effectiveness, unit cost of electricity and expected plant life. The thermo-economic performance of the proposed system is compared with system “C” without energy recovery option. Findings reveal the need to recover thermal energy associated with the discharged brine for humidification and dehumidification desalination system having ineffective/poor component effectiveness, especially the humidifier. The proposed system shows that the cost of freshwater for system C can be reduced by about 15.23% with energy recovery in system A. The GOR of system C is improved by about 23.1%, whereas the RR, productivity and SEEC of system C are improved by about 23.3% each. The conditions at which the energy recover is effective are also shown in the results

Esheatpac is an electricity storage system that combines heat pump, steam accumulator, and steam-water cycles technologies. It includes a heat pump, powered by an electric compressor, which produces saturated steam that is stored in steam accumulators as pressurized liquid water. Later, this steam produces electricity in a turbo-generator. Combination of efficiency of heat pump and Rankine cycle heat rate allows reaching efficiencies of up to 100% or higher, without requiring any auxiliary fuel. Efficiencies of up to 124.5% can be achieved by providing natural gas, with the combination of heat pumps with COP equals 2.65 and Rankine cycles with heat rate of 47%. The above means that it is possible to extract from the system the same or higher amount of electricity that enters it, after remaining stored for the time required, up to almost 25% more. Esheatpac is an optimal solution for when it is required to store large amounts of electricity and medium discharge times. Today, the only storage systems that meet these conditions are pumped hydro storage (PHS) and compressed air energy storage (CAES). Compared to PHS, Estheapc presents the advantages of its better performance, a maximum of 85%, and less environmental and public opposition problems, in addition to the limitations to find suitable locations. Compared to CAES, it presents the advantages of its better performance, 50% in current plants, and much lower storage capacities, on the order of seven times less, which also means a lower material investment.

Component optimization studies during the last twenty years, point to the use of ground source heat pump systems to minimize building heating and cooling costs. Modern computational tools enable building energy simulation for a typical year with a time step of the order of minutes. This allows improved insight in the details of its transient operation and may significantly affect the form of the objective function employed in the component optimization procedure, as demonstrated in this paper. A 3-zone residential building located in Volos, Greece, is modelled along with its chiller -boiler or heat pump, hydronic distribution system and their controls, in the TRNSYS 16 environment. Yearly performance of the building with the reference, chiller-boiler system, is compared to that of the alternative, ground source heat pump system. Comparative year-round simulations are employed to demonstrate the expected transient and overall energy balance effects of control settings, chiller or heat pump COP characteristics, equipment sizing and other design parameters.