DOES THE NOVEL DUAL SOURCE HEAT PUMP (DSHP) OUT-PERFORM THE IDEAL DSHP? EXPERIMENTATION VERSUS SIMULATION OF DSHP BASED THERMODYNAMIC IRREVERSIBILITY OF THE THROTTLE VALVE

Purpose: The air-source heat pumps are associated with continuous frosting problems. To ensure a more energy efficiency technology, the novel dual-source heat pump (DSHP) was developed. This article aims to confirm and compare the energy performance of the novel dual-source heat pump (DSHP) with the performance of an ideal heat pump. Methods: We applied an experimental analysis from an installed DSHP system with converters and other components to obtain the energy performance of the DSHP, while the performance of an ideal pump was obtained from simulation based on the theoretical algorithm of the basic principle of the thermodynamic irreversibility of the throttle valve. Results: We found that the Ideal (simulated) DSHP has a higher coefficient of performance (COP) than the installed (experimented) DSHP. The Ideal DSHP’s COP of 4.52 is higher than the Novel DSHP’s COP, which range from 1.78 (day 3) to 2.01 (day 1). The DSHP are power efficient, which reduces carbon emission from whatever power source that is been used. Implications


INTRODUCTION
Whether for household or industry purpose, a properly insulated, double-glazed and draught-proofed building system must be constructed for the structured to effectively function.
Otherwise, a backup heating and cooling system may need to be installed, especially due to make provision for expected seasonal spells.Importantly, energy efficiency technologies are an effective solution to ensure attainment of zero emission targets in the face of increasing global attentions for resources sustainability and climate change.The traditional system such as the wood-resource and gas boiler systems are less climate compliance [1].Modern systems for building constructions use the heat pumps systems, design based on the HVAC system.The systems utilise energy from waste and/or heat recovery to power buildings' ventilation system.
The approach holds optimal environmental advantage with low emissions.and reduced energy consumptions used for building's heating and cooling control.The heat pumps system produced lower temperature, between 35 and 55 o C [2,7].
Two major heat pump systemsthe air-source heat pumps (ASHP or conventional heat pumps) and the dual-source heat pump (DSHP or the Novel heat pumps)are more energy efficient and climate compliance, and are promising for future generations of heating system [4,11].The ASHP, however, is associated with frosting glitches during the winter periods.The systems are limited by the varying and inconsistent energy performances, which are largely affected by significant seasonal variations in outdoor air temperature, as it falls off during coldest periods (heating mode) and hottest (cooling mode) [5].Thus, the compressor is excessively worked problem during low ambient temperature, making the system to utilise large amount of electricity.The novel was designed to improve on the defrosting problems during winter periods [1].It circumvents limitations of the constrained heating capacity of the novel DSHP by using the exhaust air as part of the heat source.The heating capacity and energy performance of the heating systems are improved by the DSHP technology.This paper seeks to disclose the merits of the Novel DSHP over the Ideal heat pump.In completing the analysis, first, we consider a suitable principle of energy conservations.Because the DSHP has two evaporators and an internal heat exchanger, the thermodynamic irreversibility of the throttle valve is a valid approximation to theoretically simulate the behaviour for the Ideal DSHP.Based on established assumptions, the coefficient of performance (COP) was computed from the simulations using intuitively conjectured and randomly generated estimates for enthalpy, entropy, heating capacity and other parameters required to compute the COP of the ideal system.Next, we complete an experiment that

ASHP AND DSHP
Heat pump systems in heating for building ventilation system combine non-renewable (e.g., fossil)-and renewable energy sources to ensure emission of reduce waste emissions.They use simple technology of heat recovery from diverse sources (air, ground, water), and then apply for hot or space water heating.There are different types of heat pumps that exist, and they mostly depend on where the heat is sourced.Generally, an air-source absorbs heats from the external air; a ground-source, that involves installation of ground pipping wors and borehole, absorbs heat from the ground; and the water source, which absorbs heat from a lake or river water [1,2,12,13].
Amongst others, the ASHP is most installed in several buildings.In humid climates with mild exterior air temperature values during the winter, the energy efficiency reduces due to the influence of defrosting energy losses [4].ASHP run series of defrosting cycles on regular basis to remove the ice layer that has built up on the heat exchanger surface.The hot gas bypass defrosting, involving hot refrigerant flowing via the compressor outlet into the defrosting pipe, the condenser outlet refrigerant re-cooling defrosting and low-pressure hot water defrosting can be built with the technology [2].The configured defrosting cycles have implications for the pricing.The compressor over works in the defrosting cycles, requires large energy to remove the ice layer, operates with more electricity and may cause reduction in energy performance of the heat pump [6,19].There is also decrease in the indoor thermal comfort due to the low hot water temperature transported to the building [10,19].
Since defrosting during low ambient temperature operation is a challenge, the system was improved by the novel DSHP technologies.DSHP, with vapour injector compressor, is a system that utilises both ambient air and exhaust air as heat sources to improve its efficiency and performance compared to the ASHP [1].It uses a two-stage evaporator design to enable mix of ambient-and exhaust air to reduce frosting during low temperature.It has an internal heat exchanger, condenser, low-pressure (LP)-and medium pressure (MP) evaporators and throttle valves.The key operation procedure of the system is that it undergoes a two-stage The vapour is compressed to a high temperature and pressure and at this stage, the outcome from the outlet of the compressor is a saturated vapor.This goes through the inlet of the condenser where it is condensed.The refrigerant follows the expansion valve to the inlet of the evaporator, and the process goes repeatedly.Thermodynamic cycle of the Ideal DSHP

DSHP WORKING PRINCIPLE
The working system, of the Ideal DSHP is comparable to the basic principle of thermodynamic related to heat pump system.The DSHP system differs from the ASHP by the ability of its (DSHP's) throttle valves to initiate thermodynamic irreversibility [15].Fig. 2 depicted the DSHP's working system, from state 1 to 8. The figure, which plots pressure against enthalpy, shows an additional evaporator where the refrigerant is mildly vapourised by the exhaust air.From state 1 to 2, refrigerant through the valves to state 3, which is the medium level evaporator, then to state 4 using the building's exhaust air to recover heat.A portion of the refrigerant follows the evaporation line and frees the heat in the IHX after the condenser in addition to the vapour injection line (State 6).The refrigerant passes via State 7 and EEV2.
Evaporator 2 (State 8) then begins the evaporation process by absorbing heat from the mixture of fresh air and exhaust air from Evaporator 1.The refrigerant vapour eventually makes its way back to the compressor after passing through the refrigerant storage tank.For efficient operation, the low-pressure evaporator will need to be heated up.Unlike a typical EVI refrigeration, that has a flash-tant, the DSHP has a missing chamber where it misses the ambient and exhaust air.The ratio of mixture can be fixed, or it can vary based on the outdoor condition [18,20].

METHODOLOGY
The paper estimates and compares the energy performance of an installed Novel DSHP with that of a simulated Ideal DSHP in order to ascertain the difference in their energy performances.We estimate and compare the COPas a measure of energy performancefor the Novel DSHP, according to the computed average of observed estimates from the experiment

EXPERIMENT
During of the experiment, the temperature was read in Ohms (Ω) but converted into degree Celsius ( 0 C).Some estimates are made about the viability of employing exhaust air for defrosting.Fig. 3 depicts the installed 5kW DSHP, and Fig. 4 depicts the attached converter, both set up for the experiment in a specialised laboratory at the Applied Science building at the University of Hull.The experiment is completed to align the specific assumptions applied for the Ideal DSHP simulations.For instance, the configurations safeguard the indoor temperature, and the outdoor air around the laboratory applies as the exhaust air to ensure a stable relative humidity.Table 1 is the lists the monitoring devices used for the experiment.
The pump control platform was used to trigger the heat pump controls and valves.When the pump starts to run, the water level builds up to a level that allows a steady increase in the water temperature.The water temperature, compressor's power consumption, fan power consumption, ambient temperature, and water flow rates were taken record of.This process was repeated five times with increment of 10-15 interval in within time range of 11:00-12:35, 15:00-15:40 and 15:15-15:55, respectively, for the 1st, 2nd and 3rd experiments.
We conduct the experiment under varying water temperature and compute the average of all the COP.The DSHP system is examined at different periods of the day (morning, afternoon and evening), outcomes which include ambient temperature, inlet and outlet water temperature, power consumption, are recorded.We compute the averages of inputs and output water temp and COP from the experiment, and compare same with the simulation (Ideal DSHP)'s outcome.

Table 1
Monitoring devices used during the experiment 1.At a saturated liquid state, the refrigerant divides into two streams in the condenser: 2. The refrigerant is in binary state (mix liquate and gas) at medium pressure throttle valve: 6.In the heat exchanger: 7. The refrigerant is at a super saturated state at the compressor:    1.16MPa =  5 .At this point, the refrigerant is at a saturated liquid state, so,  1 = 263.94KJ/Kg.Because the refrigerant through the throttling valve absorbs heat from the internal heat exchanger causes the temperature to be higher than the temperature at the inlet of the medium pressure evaporator, we assume  5 is always 5 o C higher than  2 ( 5 = 5   +  2 = 20  ).At point 5, the refrigerant is at binary state (i.e., a mixture of liquid and gas).From In the P-H diagram (Fig. 1), there is a point missing which is the outlet of the first stage compression.Assume that point is 9, and point 8 is the outlet of the second stage compression,  9 =  7 = 0.48837MPa .In an ideal situation, the compressor is 100% efficient and the    Comparing this with the result from Table 2, the evidence indicates that the COP of the Ideal DSHP (simulation) is much higher than the COP observed from the installed Novel DSHP (experiment).The Ideal DSHP's COP of 4.52 is higher than the Novel DSHP's COP, which range from 1.78 (day 3) to 2.01 (day 1).The perceived difference may not be unconnected to 13 the fact that the simulation (experiment) operates the compressor at 100% (between 70-80%) efficiency.

CONCLUSIONS
From an environmental viewpoint, energy efficiency in buildings has severe implications for global warmings and the need for sustainability.As a result, modern ventilation system utilise energy from waste and heat recovery to power heating and cooling systems.
Amongst alternative competing heating system, the Novel DSHP is considered more energy efficient.As a result, the heat pump has promising for future generations of building ventilation design.
The study completes an experiment that analyse the performance of the DSHP, comparing the outcomes with results from a simulation based on an Ideal DSHP system.The result suggests that the COP of the Ideal DSHP is higher than the COP one from the Novel DSHP.The DSHP are power efficient, which reduces carbon emission from whatever power source that is being used.
Does the Novel Dual Source Heat Pump (DSHP) Out-Perform the Ideal DSHP?Experimentation Versus Simulation of DSHP Based Thermodynamic Irreversibility of the Throttle Valve ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.9 | p.1-15 | e05231 | 2024.4 analyses the actual performance's parameters of an installed DSHP [9].Lastly, we compare the outcome of the theoretical-based simulation's COP of the Ideal DSHP with the experiment's COP on the Novel DSHP.
Fig.1depicts the working cycle of the DSHP.The refrigerant exits the condenser at low temperature and splits into two pathways.One pathway goes through the throttle valve on low temperature and the other goes into the internal heat exchanger.The refrigerant in the first pathway from the throttle valve is a combination of liquid and gas (i.e., at binary state).This binary state refrigerant uses the heat from the exhausted air and then vaporizes in the internal heat exchanger.The refrigerant in the other pathway is subcooled and then goes into the lowpressure evaporator where it is vaporised by the mixture of the exhaust and outdoor air.One of the pecks of the DSHP is the two-stage vapour compression cycle.The outcome of the two refrigerant pathways flow to the medium and low-pressure inlet port of the vapour compressor.

Table 2
is the records completed for the experiment in three different time range (11:00-12:35, 15:00-15:40, 15:15-15:55).The Table shows the average varying water (inlets and outlets) temperature, and the COP during the experiment.The average maximum COP occurs on the first day (26.06.22), when the difference amid the inlet and the outlet temperature is about 3.81 o C. Day 1 (26.06.22) records the highest average energy performance, followed by day 2 and 3, respectively.

Table 2
Experiment outcomes: averages of inputs and output water temp and COP

Table 3
and 4 presents the for the simulation outcomes.Table 3 (Panel A) shows the energy parameter at the condenser outlet, Table 3 (Panel B) show the energy parameter at the outlet of the medium pressure valve to the medium pressure evaporator and Table 3 (Panel C)

Table 3
Simulation outputs

Table 4
Simulation outputs