scholarly journals Heat pump systems: A mini review

Author(s):  
Mohammad Omar Temori ◽  
František Vranay

In this work, a mini review of heat pumps is presented. The work is intended to introduce a technology that can be used to income energy from the natural environment and thus reduce electricity consumption for heating and cooling. A heat pump is a mechanical device that transfers heat from one environmental compartment to another, typically against a temperature gradient (i.e. from cool to hot). In order to do this, an energy input is required: this may be mechanical, electrical or thermal energy. In most modern heat pumps, electrical energy powers a compressor, which drives a compression - expansion cycle of refrigerant fluid between two heat exchanges: a cold evaporator and a warm condenser. The efficiency or coefficient of performance (COP), of a heat pump is defined as the thermal output divided by the primary energy (electricity) input. The COP decreases as the temperature difference between the cool heat source and the warm heat sink increases. An efficient ground source heat pump (GSHP) may achieve a COP of around 4. Heat pumps are ideal for exploiting low-temperature environmental heat sources: the air, surface waters or the ground. They can deliver significant environmental (CO2) and cost savings.

2019 ◽  
Vol 111 ◽  
pp. 01070
Author(s):  
Gheorghe Ilisei ◽  
Tiberiu Catalina ◽  
Robert Gavriliuc

Having in sight the need for a strong reduction in CO2 emissions and the fluctuation of the price of fossil fuels, the ground source resources alongside with the ground source heat pumps are becoming more and more widespread for meeting the heating/cooling demand of several types of buildings. This article targets to develop the thermal modelling of borehole heat storage systems. Trying to emphasize some certain advantages of a GSHP (ground source heat pump) with vertical boreholes, a case study analysing a residential solar passive house is presented. The numerical results are produced using different modelling software like DesignBuilder, EED (Earth Energy Designer) and a sizing method for the length of the boreholes (ASHRAE method). The idea of sizing the length of boreholes (main design parameter and good index in estimating the system’s cost) using two different methods shows the reliability of this modelling tool. The study shows that borehole’s length of a GSHP system can trigger a difference in electricity consumption up to 22%. Moreover, this sensitivity analysis aims to prove that the design of the whole system can be done beforehand just using modeling tools, without performing tests in-situ.


Author(s):  
Yahya I. Sharaf-Eldeen

This work involves measurements, analyses, and evaluation of performance of air-source heat pump water heaters (HPWHs), and their impacts on electric utility loads. Two add-on, heat pumps (HPs) rated at 7000 BTU/h (2.051 kW) and 12,000 BTU/h (3.517 kW) were utilized. The HPs were retrofitted to two 50 gal (189.3 l) electric water heaters (EWHs) with their electric heating elements removed. A third standard EWH was used for comparison. The testing setups were fully instrumented for measurements of all pertinent parameters, including inlet and outlet water temperatures, inlet and outlet air temperatures of the HPs, temperature and humidity of the surrounding air, volume of water drawn out of the storage tanks, as well as the electric energy consumptions of the systems. Performance measures evaluated included the coefficient of performance, the energy factor (EF), and the first hour rating (FHR). The HPWH systems gave EFs ranging from 1.8 to 2.5 and corresponding energy savings (and reductions in utility peak loads) ranging from 49.0% to 63.0%, approximately. The values obtained in the summer months were, as expected, somewhat higher than those obtained in the winter ones. The average values of the EFs and energy savings (and reductions in utility peak loads) were about 2.1 and 56.0%, respectively. FHR results were much lower for the HPWHs compared with those for the standard EWH. These results show that HPWHs are much more efficient compared with standard EWHs. While the average value of the EF for the EWH was about 0.92, the HPWHs yielded EFs averaging more than 2.00, resulting in annual energy savings averaging more than 50%. The results also show that HPWHs are effective at reducing utility peak loads, in addition to providing substantial cost savings to consumers.


Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2496 ◽  
Author(s):  
Laura Carnieletto ◽  
Borja Badenes ◽  
Marco Belliardi ◽  
Adriana Bernardi ◽  
Samantha Graci ◽  
...  

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.


2019 ◽  
Vol 111 ◽  
pp. 03002 ◽  
Author(s):  
Janne Hirvonen ◽  
Juha Jokisalo ◽  
Juhani Heljo ◽  
Risto Kosonen

This study examined the cost-optimality of energy renovation on Finnish apartment buildings of different ages, built according to different energy performance requirements. Multi-objective optimization was utilized to minimize both CO2 emissions and life cycle cost (LCC). IDA-ICE simulations were performed to obtain the hourly heating demand of the buildings. Four building age classes and three heating systems (district heating, exhaust air heat pump and ground-source heat pump) were separately optimized. With district heating, it was possible to reduce emissions by 11%, while also reducing LCC. With heat pumps cost-savings could be achieved while reducing emissions by over 49%. With maximal (not cost-effective) investments, emissions could be reduced by more than 70% in all examined cases. In all cases, the cheapest solutions included solar electricity and sewage heat recovery. In old buildings, window upgrades and additional roof insulation were cost-effective. In new buildings, demand-based ventilation was included in all optimal solutions.


2019 ◽  
Vol 116 ◽  
pp. 00023
Author(s):  
Andrzej Gajewski

To limit greenhouse gases emissions caused by energy production European Union (EU) prompts heat pump as heat generator which should decrease CO2 emissions to the atmosphere. Because of the climatic conditions and low efficiency of electrical energy production and transfer in Poland it could be possible a condensing gas boiler would emit less CO2. The analysis includes ten-year temperature measurements in Białystok where is more severe climate in Poland. Due to relatively high seasonal coefficient of performance (SCOP) value heat pumps can emit less CO2 than condensing gas boiler and can be applied as ecological heat generators.


2018 ◽  
Vol 44 ◽  
pp. 00157
Author(s):  
Piotr Rynkowski

The paper presents the ground temperature analysis, heat flows and energy transferred from the soil massif by the vertical ground heat exchangers (VGHE). Three cases – with one, two and three vertical heat exchangers were compared. Their influences on the soil massif temperature in the heat exchangers area were shown. The mass flow and the temperature at the inlet and outlet side of the heat pump were measured in each circuit. Additional, the electricity consumption by the heat pump and energy supply to buffer vessel were measured. Finally, the Coefficient of Performance (COP) as a function of length of VGHE is shown for selected interval time.


Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Michela Longo

Abstract As the energy needed for heating and cooling involves a substantial amount (> 80%) of residential energy utilisation in Canada, there is a demand for ultra-efficient energy systems for heating, cooling, and power generation. Two efficient systems to assist these systems are ground-source heat pumps (GSHPs) and organic Rankine cycles (ORCs). Of particular interest, this paper presents the integration of these two systems in a parallel configuration. A transient simulation model developed in TRNSYS program has been utilised to simulate the thermal performance of the combined ORC-GSHP based microco/trigeneration system. This later supplies heating and cooling to the residential load during the heating mode as required, with the capability to switch to a charging mode, where the ORC unit is directly coupled to the ground heat exchanger (GHE), which operates as a thermal energy storage and provides energy to the GSHP. The feasibility of this combined system configuration as well as its comparison with a conventional GSHP system are investigated for use in residential application in Ottawa, Canada temperature conditions. Results disclosed that the proposed micro-cogeneration system had the operating hours and performance of the GSHP improved by the addition of the ORC unit, resulting in about 11.8% reduction in hours in the colder city of Ottawa. The COP (coefficient of performance) of the GSHP system sustained a much higher value overall due to the addition of the ORC system to maintain the GHE storage temperature. In terms of net energy reduction between the conventional GSHP system and the ORC-assisted one, results revealed that Ottawa had energy usage reduction of 82.0%, demonstrating that the addition of an ORC to provide heating and recharge the GHE of a GSHP system has many advantages that could be accomplished by the end-user.


2014 ◽  
Vol 5 (2) ◽  
pp. 173-179
Author(s):  
T. Buday ◽  
Gy. Szabó ◽  
I. Fazekas ◽  
M. Paládi ◽  
Sz. Szabó ◽  
...  

Heating with the use of ambient energy by heat pumps is a very effective way to reduce CO2 emission. However, efficiency, economic and environmental advantages depend on the type of the heat pump and the temperature of the source, the latter usually changes during the heating season. The aim of the paper is to give the annual pattern of the COP and emission as a function of the typical source temperature pattern, moreover yearly summarized energetic and emission values are also added in the case of air source, water source and ground source heat pump systems, compared to some conventional heating mode.


2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Silvia Cocchi ◽  
Sonia Castellucci ◽  
Andrea Tucci

The need to address climate change caused by greenhouse gas emissions attaches great importance to research aimed at using renewable energy. Geothermal energy is an interesting alternative concerning the production of energy for air conditioning of buildings (heating and cooling), through the use of geothermal heat pumps. In this work a model has been developed in order to simulate an air conditioning system with geothermal heat pump. A ground source heat pump (GSHP) uses the shallow ground as a source of heat, thus taking advantage of its seasonally moderate temperatures. GSHP must be coupled with geothermal exchangers. The model leads to design optimization of geothermal heat exchangers and to verify the operation of the geothermal plant.


2020 ◽  
Vol 12 (17) ◽  
pp. 7042
Author(s):  
Marco Noro ◽  
Renato Lazzarin

Until recently, solar assisted heat pumps have used solar collectors as a cold source. Solar collectors provide, when possible, direct heat, otherwise they offer temperature levels to the heat pump evaporator higher than the outside air. At the same time, solar thermal cooling exploits the solar collectors and the absorption chiller only in hot months. Photovoltaic/Thermal (PVT) modules have been available on the market in recent years for solar cogeneration, but their utilization can be problematic due to PhotoVoltaic (PV) cell damage in cases where there is no heating request. This paper considers the possibility of coupling evacuated tube collectors and photovoltaic/thermal modules to drive an absorption heat pump-based plant operating as an absorption chiller in the summertime. The cold source is the solar energy and the ground, which is recharged by the solar thermal and photovoltaic/thermal collectors and by the cooling of the absorber-condenser in mid-seasons and summer. This study analyzes the system behavior in yearly operation and evaluates the role of suitable storage tanks in two different climates, varying the size of the two solar fields and the generator tank. In the best plant configuration, a primary energy ratio of 26.6 in colder climates with cloudy skies and 20 in hotter climates with clearer skies is obtained.


Sign in / Sign up

Export Citation Format

Share Document